Atropine Resistance Research Articles

P175 PARADOXICAL RESPONSE DURING DOBUTAMINE STRESS ECHOCARDIOGRAPHY: A CASE REPORT

Abstract Background Dobutamine Stress Echo (DSE) is a test widely used in the diagnosis of ischemic heart disease. The purpose of the following work is to describe a clinical case with uncommon behaviour. Case Description: 63–year–old female with dyspnoea on mild exertion, and history of NSTEMI–ACS 5 years prior with Coronary Angiography (CA) finding of 3–vessel coronary artery disease, treated with PCI + stent (DES) of right coronary artery (CDX), untreated disease sub–occlusion of the first marginal obtuse (OM1), and chronic occlusion of the anterior interventricular artery (IVA). We decide for DSE. During 20 mcg/kg/min infusion, the patient reported dyspnoea and paradoxical bradycardia (BP) was documented on the ECG, in the absence of ST changes, with the appearance of akinesia of the basal and mid posterolateral segments and worsening of the inferior hypokinesia, present in basal conditions on Echocardiograms (EC). The BP and the alterations of the ventricular motion (VCA) did not respond to the administration of Atropine (1+1 mg) while the administration of 240 mg of Aminophylline (AM) restored the HR and the VCA to baseline values. The CA demonstrated patency of the CDX with the presence of collateral circulation for IVA and occluded OM1. Discussion This case is characterized by the presence of a double paradox: the BP and the Atropine–Resistance (AR). BP during DEB, as demonstrated in previous studies, occurred in 8% of cases, with signs of significant coronary artery disease in 57% of cases. The BP is an expression of ischemia only in just over half of the patients, in the rest of the cases it appeared referable to the Bezold–Jarish reflex, a vagal reflex determined by the stimulation of the intracardiac mechanoreceptors. In our case, the presence of AR seems to exclude the possibility that bradycardia is due to this reflex. The appearance of paradoxical bradycardia during DSE is a rare complication and can lead to premature termination of the test with inconclusive results. In our case, the BP and the AR confirm the positivity of the test also in consideration of the response to the AM antagonist of Adenosine, which accumulates during ischemia. Conclusions This uncommon response to DSE, where AR and AM response in addition to BP could identify patients with severe coronary artery disease in whom the ischemic response is driven by adenosine accumulation, rather than a vagal reflex responding to atropine administration.

Characterisation of nerve-mediated ATP release from bladder detrusor muscle and its pathological implications.

This study aims to characterise the molecular mechanisms that determine variability of atropine resistance of nerve-mediated contractions in human and guinea pig detrusor smooth muscle. Atropine resistance of nerve-mediated contractions and the role of P2X1 receptors, were assessed in isolated preparations from guinea pigs and also humans with or without overactive bladder syndrome, from which the mucosa was removed. Nerve-mediated ATP release was measured directly with amperometric ATP-sensitive electrodes. Ecto-ATPase activity of guinea pig and human detrusor samples was measured in vitro by measuring the concentration-dependent rate of ATP breakdown. The transcription of ecto-ATPase subtypes in human samples was measured by qPCR. Atropine resistance was greatest in guinea pig detrusor, absent in human tissue from normally functioning bladders, and intermediate in human overactive bladder. Greater atropine resistance correlated with reduction of contractions by the ATP-diphosphohydrolase apyrase, directly implicating ATP in their generation. E-NTPDase-1 was the most abundantly transcribed ecto-ATPase of those tested, and transcription was reduced in tissue from human overactive, compared to normal, bladders. E-NTPDase-1 enzymic activity was inversely related to the magnitude of atropine resistance. Nerve-mediated ATP release was continually measured and varied with stimulation frequency over the range of 1-16Hz. Atropine resistance in nerve-mediated detrusor contractions is due to ATP release and its magnitude is inversely related to E-NTPDase-1 activity. ATP is released under different stimulation conditions compared with ACh, implying different routes for their release.

Changes in the Neuronal Control of the Urinary Bladder in a Model of Radiation Cystitis.

Currently, we have assessed the neuronal control of the urinary bladder in radiation cystitis and whether interstitial cells contribute to the condition. Fourteen days after bladder irradiation (20 Gy), rats were sedated and the urinary bladder was cut into two sagittal halves where electrical field stimulation (EFS; 5-20 Hz) was applied on the pelvic nerve afferents or stretch (80 mN) on one-half of the bladder, while contractions were registered on the contralateral half of the bladder in the absence and presence of increasing doses of imatinib (1-10 mg/kg; inhibitor of c-kit-positive interstitial cells), atropine (1 mg/kg; to block muscarinic M3 receptors), or pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (2 mg/kg; P2X1 purinoceptor antagonist). Urinary bladders were also excised for organ bath experiments, Western blot, quantitative polymerase chain reaction, and immunohistochemistry. In vivo, EFS contractions were enhanced after irradiation, and imatinib (1-10 mg/mg) inhibited contractions by EFS and stretched dose-dependently in controls but not in irradiated bladders. In the irradiated bladder in vitro, atropine resistance was increased and imatinib (100 µM) inhibited contractions by EFS and agonists (ATP, methacholine) in irradiated bladders and controls. The urinary bladder expressions of P2X1 purinoceptors, muscarinic M3 receptor, choline acetyltransferase, c-kit, and the agonist of c-kit, stem cell factor, were not changed by irradiation. In conclusion, bladder irradiation affects several levels of neuronal control of the urinary bladder. Interstitial cells may contribute to some of the symptoms associated with radiation cystitis.

Clinical study of effect of penehyclidine hydrochloride and atropine sequential therapy in the treatment of severe acute organophosphorus pesticide poisoning

To investigate the clinical efficacy of penehyclidine hydrochloride sequential to atropine in severe acute organophosphorus pesticide poisoning (AOPP). A retrospective analysis of the clinical data of 180 patients with severe AOPP admitted to the Emergency Center of Wuwei City People's Hospital from January 2007 to August 2011 was conducted. The patients were divided into penehyclidine hydrochloride sequential to atropine group, atropine group and penehyclidine hydrochloride group according to difference of anti-choline drugs using, with 60 cases in each group. The complication rate, time of recovery of cholinesterase (ChE) activity to 70％, hospital stay time and cost, the cure rate, mortality rate in three groups were analyzed. In penehyclidine hydrochloride sequential to atropine group, except for 1 case of cancer of gastric cardia with poisoning after operation showing intermediate syndrome of poisoning, the remaining patients did not have any complication, and the incidence of complications was 1.67％.No death occurred in all the patients, and the cure rate was 100.00％.Time of recovery from ChE activity to 70％ was (4.0 ± 1.1 ) days; hospital stay was (7.0 + 2.2) days; hospital expenses were (6268 ± 238 ) yuan. In atropine group, 3 patients were found to have atropine resistance, 3 patients showed intermediate syndrome, rebound was observed in 2 cases, atropine poisoning in 2 patients, and the incidence of complications was 16.67％.Three patients died of respiratory or circulatory failure, and the mortality rate was 5.00％.Fifty-seven patients were cured, the cure rate was 95.00％.The time of ChE activity recovery to 70％ was (8.0 ± 0.9) days. Hospital stay was (12.0 ± 2.1) days. Hospital expenses were (7160 ± 110) yuan. In penehyclidine hydrochloride group, 1 patient was found to have respiratory failure, 1 case suffered from pulmonary edema, and the complication rate was 3.33％.Two patients died, the mortality rate wan 3.33％.Fifty-eight patients were cured, the cure rate was 96.67％.The time of ChE activity recovery to 70％ was (6.0 ± 0.7) days, hospital stay was (9.0 ± 1.5) days, and hospital expenses were (7921 ± 230) yuan. Compared with atropine group, penehyclidine hydrochloride sequential to atropine group had a low death rate, high cure rate, less complications, ChE activity recover fast, short hospital days, and the hospitalization expenses were lower than that of the single use of atropine or single use of penehyclidine hydrochloride group, and the differences were statistically significant (all P＜0.01). In treatment of severe AOPP by penehyclidine hydrochloride sequential to atropine, curative effect was more significant, with fewer adverse reactions, short hospital stay, and lower cost.

Influence of age and bladder dysfunction on the contractile properties of isolated human detrusor smooth muscle

To test the hypothesis that the in vitro contractile properties of human detrusor smooth muscle are dependent on the age, gender and lower urinary tract pathology of the patient. Contractions were elicited in isolated human detrusor smooth muscle preparations by nerve-mediated electrical field stimulation, agonist application (carbachol, α,β-methylene ATP and high-K solutions) or direct muscle electrical stimulation. Biopsies (n = 227) were obtained from four groups of patients with: stable bladders (control), bladder outlet obstruction (BOO), idiopathic (IDO), or neurogenic (NDO) detrusor overactivity. The magnitude of nerve-mediated contractions declined as a function of patients' age in each of the BOO, IDO and NDO groups but not in the control group. Contractions elicited by direct muscle activation (10 µM carbachol or electrical stimulation with 20 ms pulses in the presence of 1 µM tetrodotoxin) did not vary with patient age. Carbachol contractions were significantly smaller in samples from NDO bladders. Atropine resistance was more prevalent in the pathology groups compared with the control group and was greatest in the IDO group. There was no influence of age in the prevalence or magnitude of atropine-resistant contractions in any group. Muscle excitability to direct electrical stimulation was similar in all groups. In the human bladder there is no evidence for a decline of detrusor smooth muscle contractility or excitability as a function of age, nor any gender difference or presence of pathology. In the pathology groups there was evidence for a decline of functional innervation with age.

Neurotransmission and viscoelasticity in the ovine fetal bladder after in utero bladder outflow obstruction.

Fetal bladder outflow obstruction, predominantly caused by posterior urethral valves, results in significant urinary tract pathology; these lesions are the commonest cause of end-stage renal failure in children, and up to 50% continue to suffer from persistent postnatal bladder dysfunction. To investigate the physiological development of the fetal bladder and the response to urinary flow impairment, we performed partial urethral obstruction and complete urachal ligation in the midgestation fetal sheep for 30 days. By electrical and pharmacological stimulation of bladder strips, we found that muscarinic, purinergic, and nitrergic mechanisms exist in the developing fetal bladder at this gestation. After bladder outflow obstruction, the fetal bladder became hypocontractile, producing less force after nerve-mediated and muscarinic stimulation with suggested denervation, and also exhibited greater atropine resistance. Furthermore, fetal bladder urothelium exerted a negative inotropic effect, partly nitric oxide mediated, that was not present after obstruction. Increased compliance, reduced elasticity, and viscoelasticity were observed in the obstructed fetal bladder, but the proportion of work performed by the elastic component (a physical parameter of extracellular matrix) remained the same. In addition to denervation, hypocontractility may result from a reduction in the elastic modulus that may prevent any extramuscular components from sustaining force produced by detrusor smooth muscle.

A NEW APPROACH TO RECORDING THE ELECTROMYOGRAPHIC ACTIVITY OF DETRUSOR SMOOTH MUSCLE

Extracellular recordings from the whole intact mammalian bladder of the electrical events leading to contraction of the organ have been elusive for almost 50 years despite the widespread potential applications of such a technique. The principal problem is the need to isolate the small real signals reflecting membrane depolarization from the large electromechanical artifact generated as the organ contracts. In this preliminary study we determined whether electrical signals may be isolated and verified as biological using extracellular bipolar reversible suction electrodes. Six whole excised guinea pig bladders were mounted in an especially constructed organ bath. Electrical activity resulting from nerve stimulation of the organ was recorded using a novel 10 bipolar Pt/PtCl suction electrode simultaneously with changes in intravesical pressure. Mechanical and pharmacological control experiments were performed to determine the true origin of these signals. A predominantly biphasic electrical signal of a mean amplitude plus or minus standard deviation of 647 plus or minus 301 microV. and a mean duration of 293 plus or minus 51 milliseconds was consistently recorded from the serosal surface of all guinea pig bladders. In all cases the electrical signal and mechanical response to stimulation were completely abolished by 1 microM. tetrodotoxin. The signal always preceded any change in intravesical pressure. It was sensitive to changes in the CaCl2 concentration of the superfusate, abolished by purinergic but not cholinergic neuromuscular blockade and independent of electromechanical artifact. In this preliminary report we describe a novel technique by which nerve mediated detrusor electrical activity leading to contraction of the whole intact guinea pig bladder may be isolated from artifact and verified as real. We hope that development of this technique may enable its application to the in situ human bladder. However, to our knowledge whether electromyographic activity may be recorded from human detrusor remains to be determined.

Response of the human neurogenic bladder induced by intramural nerve stimulation

The detrusor contraction induced by intramural nerve stimulation in human neurogenic bladders was investigated in comparison with control bladders. All the cases with the neurogenic bladder underwent ileocystoplasty in order to resolve intractable incontinence and/or vesicoureteral reflux due to low bladder compliance or severe detrusor uninhibited contraction. 1. The dose-response curve and ED50 value for KCl were not different between neurogenic and control bladders. 2. The response of neurogenic bladders induced by intramural stimulation was significantly stronger than that of control bladders. 3. After application of 10(-6) M atropine remaining contraction of neurogenic bladders was significantly greater than that of control bladders, i.e. 28.4% and 3.7% respectively. However, 10(-6) M tetrodotoxin almost completely inhibited the detrusor contraction in both groups. 4. The subthreshold KCl (5 mM or 10 mM) enhanced the detrusor contractility significantly in control bladders compared to neurogenic bladders. 5. After bathing medium was replaced into Ca-free Krebs' solution, the contractile response was decreased. The contraction of neurogenic bladders in Ca-free solution persisted longer than that of controls. In conclusion, though there was no intrinsic difference in detrusor contractility, contractile response to electrical field stimulation, atropine resistance, enhancement of response by potassium, and contractility in Ca-free solution were significantly different between neurogenic and control bladders.

Bladder Purinergic Receptorsa

In rabbits the contractile response of the urinary bladder is only partially due to cholinergic innervation since atropine does not completely block neuron ally mediated contractions. In the human bladder this atropine resistance is controversial with some reporting atropine resistance in­ vitro while others have stated that the atropine resistance is also tetrodotoxin resistant. Results of the present investigation demonstrate that an atropine resistant, tetrodotoxin sensitive contraction can be evoked in some, but not all human bladder strips. Evidence accumulated over the past few decades indicates that this atropine resistant contraction may be mediated by ATP or a related purine compound. Studies presented herein are designed to develop a radioligand assay for this receptor. Initial studies indicated that the hydrolysis resistant ATP analog (3,1' methylene ATP offers several advantages over ATP as a potential radio ligand. It is only slowly hydrolyzed by endogenous ATPase and does not inhibit the hydrolysis of ATP indicating that it probably does not bind to the active sites of endogenous ATP hydrolyzing enzymes. In addition (3,1' methylene ATP is 10-100 fold more potent than ATP itself in stimulating contractions of the urinary bladder in-vitro. The radio ligand binding assay herein described can be used to quantitate the density of receptors, an essential step for determining the role of this system in urinary bladder function and dysfunction. Application of this assay could form the foundation for development of a new class of therapeutic agents for the treatment of urinary bladder dysfunction based on modulation ofthe nervous system. (J. Ural., 144: 176-181, 1990) The postganglionic nerve evoked contractile response of the urinary bladder of nearly all vertebrate species including man is only partially blocked by antimuscarinic agents such as atropine and scopolamine ' and is relatively unaffected by alpha and beta adrenergic or nicotinic antagonists.! The most likely explanation for this response is that in addition to acetylcho­ line, released by cholinergic nerves, another neurotransmitter released by non-adrenergic, non-cholinergic nerves contributes to the contraction. The presence of these neurons has been alluded to in the early literature by Langley2 and their existence has been suggested throughout the gastrointestinal tract as well as other organs including lung, trachea, esophagus, cardiovas­ cular system, and seminal vesicles.! In the human female blad­ der these nerves have been estimated to be responsible for 50% of the contractile response. 3 Evidence accumulated over the past few decades suggests that the neurotransmitter utilized by these neurons is most likely a purine nucleotide or analog and these nerves have therefore been coined purinergic by Burns­ tock Functionally these neurons are those that produce an effect on the innevated tissue in the presence of both atropine and guanethidine. Although other explanations for the atropine resistant re­ sponse have been put forth including the presence of a barrier to the penetration of atropine, there is little evidence for them. Many substances other than ATP have been explored as can­ didates for mediating the atropine resistant contraction. These include catecholamines, 5-hydroxytryptamine, cyclic AMP, his­ tamine, prostaglandins, alanine, arginine, glycine, glutamic acid, gamma amino butyric acid, bradykinin and substance P.! These substances have been rejected as candidates by most workers since they a) were either inactive or did not mimic the nerve mediated response, b) specific antagonists for these sub

Bladder Purinergic Receptors

In rabbits the contractile response of the urinary bladder is only partially due to cholinergic innervation since atropine does not completely block neuronally mediated contractions. In the human bladder this atropine resistance is controversial with some reporting atropine resistance in-vitro while others have stated that the atropine resistance is also tetrodotoxin resistant. Results of the present investigation demonstrate that an atropine resistant, tetrodotoxin sensitive contraction can be evoked in some, but not all human bladder strips. Evidence accumulated over the past few decades indicates that this atropine resistant contraction may be mediated by ATP or a related purine compound. Studies presented herein are designed to develop a radioligand assay for this purinergic receptor. Initial studies indicated that the hydrolysis resistant ATP analog β, γ methylene ATP offers several advantages over ATP as a potential radioligand. It is only slowly hydrolyzed by endogenous ATPase and does not inhibit the hydrolysis of ATP indicating that it probably does not bind to the active sites of endogenous ATP hydrolyzing enzymes. In addition β, γ methylene ATP is 10-100 fold more potent than ATP itself in stimulating contractions of the urinary bladder in-vitro. The radioligand binding assay herein described can be used to quantitate the density of purinergic receptors, an essential step for determining the role of this system in urinary bladder function and dysfunction. Application of this assay could form the foundation for development of a new class of therapeutic agents for the treatment of urinary bladder dysfunction based on modulation of the purinergic nervous system.

Autonomic nervous control of nasal vasculature and airflow resistance in the anaesthetized dog.

1. In pentobarbitone-anaesthetized dogs with constant-flow vascular perfusion of nasal mucosa on both sides, nasal airway resistance, vascular resistance, vascular capacitance (via changes in total venous outflow) and blood flow in the anterior and posterior venous systems were measured. 2. Electrical stimulation of the cut peripheral ends of the cervical sympathetic trunk, caudal nasal nerve, or major palatine nerve increased vascular resistance and decreased vascular capacitance and airway resistance. Propranolol and atropine had no effect on the responses while bretylium completely abolished them; phentolamine greatly lessened the vascular resistance response and partially decreased the vascular capacitance and airway responses. Hence, sympathetic stimulation causes constriction of the resistance vessels via alpha-adrenergic mechanism and constriction of capacitance vessels via alpha-adrenergic as well as some non-adrenergic and non-cholinergic mechanisms. 3. Denervation of the cervical sympathetic trunk, caudal nasal nerve and major palatine nerve decreased nasal vascular resistance and increased vascular capacitance and airway resistance, suggesting tonic sympathetic discharge to nasal mucosa via caudal nasal and major palatine nerves. 4. Electrical stimulation of the nerve of pterygoid canal decreased vascular resistance but increased vascular capacitance (in the posterior venous system) and airway resistance to low-voltage stimulation (below 10 V), and decreased vascular capacitance (in the anterior venous system) and airway resistance to high-voltage stimulation (above 10 V). Hexamethonium reversed the vascular resistance response as well as vascular capacitance and airway responses to high-voltage stimulation. Bretylium and phentolamine enhanced the vascular resistance response and reversed vascular capacitance and airway resistance responses to high-voltage stimulation. Hence, low-voltage stimulation results in parasympathetic dilatation of resistance and capacitance vessels whereas high-voltage stimulation results in parasympathetic dilatation of resistance vessels and sympathetic constriction of capacitance vessels. The parasympathetic vasodilatation was atropine resistance and the sympathetic vasoconstriction was partially via alpha-adrenergic mechanisms. 5. Denervation of the nerve of pterygoid canal did not affect vascular resistance, vascular capacitance or airway resistance suggesting negligible tonic parasympathetic and sympathetic discharges to nasal blood vessels via the nerve. 6. Simultaneous optimal stimulation of sympathetic and parasympathetic nerves resulted in vasoconstriction, especially in capacitance vessels, suggesting sympathetic predominance over parasympathetic control.

Deafferentation of the vestibular organ: Effects on atropine-resistant EEG in rats

Cortical and hippocampal EEG patterns that persist after atropine sulfate administration are defined as atropine-resistant. In the rat, such patterns are movement-related, cortical low-voltage fast activity (LVFA) and movement-related, hippocampal rhythmic slow activity (RSA or “theta”). A close relationship exists between head movement and activation of atropine-resistant EEG. In the present study, we asked whether manipulation of vestibular sensory input would affect atropine-resistant EEG. To allow experimenter control, 6 vestibular-intact rats were made cataleptic with haloperidol and were then injected with atropine sulfate. Movement of the rats* heads by the experimenter (passive head movement) failed to activate atropine-resistant EEG. These animals were then rotated on a turntable. Such vestibular stimulation, the effectiveness of which was reflected by postrotatory ocular nystagmus, &lso failed to activate atropine-resistant EEG. These and 5 other rats were then subjected to surgical or chemical deafferentation of the labyrinth. They were tested for EEG atropine resistance before and after this surgery. Although atropine-resistant EEG patterns in response to active bodily movements still appeared after vestibular deafferentation, the frequency of hippocampal RSA during active movement was reduced with or without atropine. In contrast, &n atropine-sensitive component in the hippocampal EEG during immobility was not changed by vestibular deafferentation. We conclude that vestibular reafferent feedback is neither necessary nor sufficient for the atropine-resistant EEG, but that such feedback from active movement has a modulatory effect on hippocampal RSA.

An in vitro pharmacological study of the human trigone--a site of non-adrenergic, non-cholinergic neurotransmission.

Muscle strips from the human detrusor and trigone were studied in vitro. The detrusor muscle contracted strongly to both cholinergic receptor stimulation with carbachol and to electrical field stimulation. There was no evidence of atropine resistance in the detrusor strips. The superficial trigone responded maximally to alpha-adrenergic receptor stimulation but also produced a significant cholinergic response. Intramural nerve stimulation in the presence of both atropine and phentolamine produced a residual non-adrenergic, non-cholinergic (NANC) response of 40% of its maximum at 5 Hz. Electrical stimulation, particularly at the lower frequencies of stimulation, produced relaxation responses in 40% of the superficial trigonal muscle strips. These relaxations were not blocked by atropine, phentolamine or propranolol, but were abolished by tetrodotoxin. The possible role of the cholinergic "input" to the superficial trigone and the importance of the NANC excitatory and inhibitory innervation in preventing vesico-ureteric reflux and and in aiding bladder neck opening is discussed.

Autonomic nervous control of the endocrine secretion from the isolated, perfused pig pancreas

The effect of electrical stimulation of the splanchnic and the vagus nerve supply to isolated, perfused pig pancreas on the secretion of insulin, glucagon and pancreatic polypeptide (PP) was investigated. Functional integrity of the autonomic nerve supply was assessed by the effect of nerve stimulation on vascular resistance and exocrine secretion. Splanchnic nerve stimulation increased glucagon and PP output (2 to 3-fold) and inhibited insulin output (by 42%). Propranolol abolished the effect on PP and glucagon secretion, but did not affect the inhibition of insulin secretion. Phenoxybenzamine abolished the inhibition of insulin secretion, reduced the effect on glucagon secretion and enhanced the effect on pancreatic polypeptide secretion. Combined α- and β-adrenergic blockade abolished all effects of splanchnic nerve stimulation. Vagus nerve stimulation increased the secretion of all 3 hormones (PP: up to 30-fold, insulin and glucagon: 3 to 5-fold). The effect on insulin and PP-secretion was mimicked by acetylcholine at 10 −7−10 −6 M, whereas glucagon secretion was inhibited. The effect of vagus nerve stimulation on insulin and PP secretion was augmented by physostigmine, and inhibited (but not abolished) by atropine at 10 −7−10 −6 M. The effect on glucagon secretion was inhibited by physostigmine and unaffected by atropine. It is concluded that all of the effects of splanchnic nerve stimulation on insulin and PP secretion can be explained by interactions of norepinephrine with excitatory β-receptors on PP-cells and inhibitory receptors on the insulin cells. Both cell types are also stimulated via muscarinic cholinoceptors, but the partial atropine resistance suggests that other transmitters participate in vagal activation. The nervous regulation of glucagon secretion is complex and may involve the peptidergic innervation of the pancreatic islets.

Innervation of the child urinary bladder.

Muscle strips from the fundus, trigonum and distal ureters obtained from children at operations for vesico-ureteric reflux were studied using histochemical and immunohistochemical methods, and electrical nerve stimulation in an organ bath. A rich supply of cholinergic nerves was found and despite a partial atropine resistance the neurophysiological experiments indicated that the transmitter causing contraction of the detrusor muscle is acetylcholine. Imipramine, which is used in the treatment of enuresis, had no anticholinergic effect on the bladder in the doses used clinically. The adrenergic innervation was very sparse except around the ureter orifices. No contractile alpha-adrenoceptors could be detected but beta receptor mediated relaxation was found, which was neither of the beta 1 nor beta 2 type. A third type of beta receptor is postulated. Peptidergic nerves containing vasoactive intestinal peptide, VIP, were demonstrated in a few nerve terminals running along bundles of smooth muscle. No nerves containing enkephaline, somatostatine or substance P were found. VIP affected the detrusor muscle indicating a possible role as a modulator of transmitter action, while substance P had no effect. The anticholinergic and calcium antagonistic drug terodiline inhibited all muscle activity, whether it was induced by nerve stimulation, cholinergic drugs or a potassium rich solution, making it suitable for treatment of diurnal enuresis.

Atropine Blockade of Nerve‐mediated Stimulation of the Human Detrusor

The effect of atropine on the isometric contractile response of isolated human detrusor muscle strips to electrical field stimulation has been studied. A 94.1% reduction in the response in the presence of tetrodotoxin demonstrated the neuronal nature of the stimulus. Atropine caused a 92.7% inhibition of the response. It was concluded that the nerve-mediated stimulus in human detrusor is cholinergic in nature and that "atropine resistance" does not occur in man.

Comments on the atropine resistance of the neurogenic contractile response of the rat detrusor muscle.

The resistance to atropine or scopolamine of the neurogenic contractile response to field stimulation of intramural nerves of the rat detrusor was studied during the early phase of Wallerian degeneration in vitro and in vivo. The neurogenic contractile response to low frequency stimulation of control bladders was completely resistant to atropine or scopolamine in vitro. As a matter of fact the response was enchanced by the drugs. In vivo a transient shortening of the response could be seen. 26-34 h after bilateral extirpation of the pelvic ganglia there was prominent degeneration activity in the bladders in vitro as well as in vivo. Atropine or scopolamine inhibited this activity in vivo but enhanced it in vitro. The neurogenic contractile response to field stimulation of the bladder nerves was blocked in vivo but not in vitro by the antimuscarinic drugs 26-34 h after neurectomy. The results support the concept that the excitatory neurotransmission in the detrusor is essentially cholinergic. An explanation of the difference between the in vivo and the in vitro results based on differences in degree of blockade of pre- and post-junctional muscarinic receptors and diffusion of the antimuscarinics in the tissue is proposed.

Atropine resistance in asthma: definition and provisional hypothesis.

Out of a group of 55 asthmatics, 16 fitted the strict definition of atropine resistance (less than 20% FEV1 response to inhaled anticholinergic drugs, with a 20% or more FEV1 response to subsequent inhalation of beta 2-adrenergic stimulants). 26 were defined as atropine responsive in that they had a 20% or more FEV1 response to anticholinergic drugs. Significantly more atopic than non-atopic asthmatics were in the atropine-resistant group (chi 2 = 6.12; p less than 0.025). Atropine resistance is not related to age. It is probably due to excessive vagal activity resulting from sensitization of vagal irritant receptors by antigen. Atropine resistance appears to be ameliorated by treatment with corticosteroid drugs or disodium cromoglycate. These features suggest a link between allergic and vagal components in asthma.

Atropine Resistance of Transmurally Stimulated Isolated Human Bladder Muscle

Human detrusor strips were obtained from patients undergoing reimplantation of ureters because of reflux, transvesical prostatectomy, or cysto-urethrectomy en bloc because of bladder malignancy. The strips were electrically stimulated. A frequency-dependent contractant response was obtained that was potentiated by physostigmine and abolished by tetrodotoxin. The maximum response approximately equaled that of acetylcholine in a maximum concentration. In most bladder preparations from patients without known functional bladder disturbances, atropine (0.01 to 0.1 μM.) had a marked inhibitory effect, and at concentrations exceeding 1 μM the blockade was complete. In strips obtained from patients undergoing transvesical prostatectomy, and who also had a cystometrically verified unstable bladder, there was a varying degree of atropine resistance, with some preparations showing a 50 per cent resistance to atropine. Prazosin, phentolamine, yohimbine, guanethidine, clonidine, and noradrenaline had no consistent effects on the electrically induced bladder contraction. Nifedipine and nimodipine caused a maximum of 65 per cent inhibition of the response. Addition of nimodipine to atropine-resistant strips when maximum atropine inhibition had been reached abolished the contractions. Omitting calcium from the bath solution rapidly abolished the electrically induced contraction. It is suggested that in the normal human bladder the contraction induced by electrical stimulation is mainly atropine sensitive. However, in the functionally disturbed bladder, part of the bladder contraction is atropine resistant, a finding that may have clinical implications.

Effect of atropine and methiamide on vagally induced gastric acid secretion and gastrin release in anesthetized cats.

Gastrin release and HCl secretion was induced by electrical vagal stimulation in anesthetized cats. Both atropine (0.1-0.3 mg/kg) and methiamide (4-20 mg/kg) inhibited the HCl secretion (by approximately 60 and approximately 80 %). On the other hand, neither atropine (0.2-2 mg/kg) nor methiamide (20 mg/kg) inhibited the vagally induced gastrin release. Possible explanations of the atropine resistance of the vagal gastrin release mechanism are discussed.