Contractile Effects Of Substance Research Articles

Tachykinins contract trachea from Fischer 344 rats by interaction with a tachykinin NK 1 receptor

The contractile effect of substance P, neurokinin A, carbachol and serotonin (5-HT) on isolated Fischer 344 rat trachea was studied. Contractions of two distal tracheal rings were measured isometrically in a 2-ml organ bath. Cumulative concentration-response curves were obtained for carbachol (EC 50 ring 1:1.6 × 10 −7 M and ring 2:2.2 × 10 −7 M) and for 5-HT (EC 50 ring 1: 10.2 × 10 −7 M and ring 2:10.5 × 10 −7 M). Non-cumulative administration of substance P and neurokinin A (10 −8 to 10 −5 M) caused a concentration-dependent contraction with an EC 50(× 10 −7 M) of 1.10 ± 0.27 and 1.97 ± 0.45 respectively. The maximal contraction was 32.6 ± 2.5% (substance P) and 32.6 ± 1.5% (neurokinin A) of the maximal contraction with carbachol. In contrast, neither substance P nor neurokinin A caused contraction of trachea from BDE rats. The tachykinin NK 1 receptor agonist, Ac[Arg 6, Sar 9, Met(O 2) 11]substance P-(6–11), caused a concentration-dependent contraction with an EC 50(× 10 −9M) of 1.38 ± 0.09 and a maximal effect of 25.5 ± 2.1% of the maximal contraction with carbachol. The tachykinin NK 2 receptor agonist, [β-Ala 8]neurokinin A-(4–10), had a small contractile effect at 10 −6 M (8.4 ± 0.8% of the maximal contraction with carbachol) while the tachykinin NK 3 receptor agonist, senktide, had no effect up to 3.3 × 10 −6 M. The tachykinin NK 1 receptor antagonist, (±)-RP67580 ((3 aR, 7 aR)-(7,7-diphenyl-2-(1-imino-2-(2-methoxyphenylethyl)-perhydraisoinotol-4-one))) (3 × 10 −9 to 10 −7 M), produced a concentration-dependent rightward shift of the concentration-response curve for neurokinin A (Schild plot: slope 1.13, x-intercept 8.4). The tachykinin NK 2 receptor antagonist, SR48968 (( S)- N-methyl- N[4-(4-acetylamine-4-phenylpiperidino)- 2-(3,4-dichlorophenyl) butylbenzamide) (10 −8 to 10 −6 M), had no major effect on the concentration-response for neurokinin A. We conclude that substance P and neurokinin A contract Fischer 344 rat trachea mainly by interaction with a tachykinin NK 1 receptor.

Effects of cromakalim on bradykinin-, histamine- and substance P-induced airway microvascular leakage in the guinea-pig

The effects of cromakalim on the increase in microvascular permeability induced by histamine, substance P or bradykinin in guinea-pig airways were studied in vivo. Extravasation of i.v. injected Evans blue dye was used as an index of permeability. We also studied the effects of cromakalim on the contractile effect of substance P, histamine or bradykinin on the isolated guinea-pig main bronchus and on the contractile response of isolated guinea-pig main bronchi to electrical field stimulation. Cromakalim (30 to 300 μg · kg −1) did not inhibit the increase in microvascular permeability induced by histamine (30 μg · kg −1) in guinea-pig airways and potentiated (30 and 100 μg · kg −1) the effects of substance P (0.3 μg · kg −1) in trachea, main bronchi and proximal intrapulmonary airways. In contrast, cromakalim (30 and 300 μg · kg −1) reduced the increase in microvascular permeability induced by bradykinin (0.3 μg · kg −1). However, a significant potentiation of the effects of bradykinin was observed with cromakalim (100 μg · kg −1) in main bronchi and intrapulmonary airways. In the isolated guinea-pig main bronchus, the contractile effects of bradykinin, histamine and substance P were not modified by cromakalim (10 −5 M). Conversely, cromakalim (10 −5 M) significantly reduced both cholinergic and noncholinergic contractile responses induced by electrical field stimulation of the isolated guinea-pig main bronchus. In conclusion, cromakalim can partially inhibit the increase in microvascular permeability induced by i.v. bradykinin. It is suggested that this effect might occur through inhibition of the nonadrenergic noncholinergic excitatory (NANC) nerves preventing release by bradykinin of inflammatory neuropeptides such as substance P.

Immunohistochemical distribution and contractile effects of substance P (SP) and calcitonin generelated peptide (CGRP) on the opossum sphincter of ODDI(SO)

Immunohistochemical distribution and contractile effects of substance P (SP) and calcitonin generelated peptide (CGRP) on the opossum sphincter of ODDI(SO)

NK 2 tachykinin receptors and contraction of circular muscle of the human colon: characterization of the NK 2 receptor subtype

The contractile effect of substance P, neurokinin A, receptor selective agonists for tachykinin receptors and NK 2 tachykinin receptor antagonists was investigated in mucosa-free circular strips of the human isolated colon. Neurokinin A and substance P produced concentration-dependent contractions which approached 80–90% of the maximal response to carbachol. Neurokinin A was about 370 times more potent than substance P. The action of neurokinin A and substance P was not modified by peptidase inhibitors (bestatin, captopril and thiorphan, 1 μM each). The NK 2 receptor selective agonist, [β3-Ala 8]neurokinin A-(4–10) closely mimicked the response to neurokinin A while NK 1 and NK 3 receptor selective agonists were active only at μM concentrations. The pseudopeptide, MDL 28,564, which is one of the most selective NK 2 ligands available, behaved as a full agonist. Responses to [β-Ala 8]neurokinin A were antagonized by NK 2 receptor selective antagonists, with the rank order of potency MEN 10,376 > L 659,877 > R 396. These data indicate that NK 2 tachykinin receptors play a dominant role in determining the contraction of the circular muscle of the human colon to peptides of this family. The NK 2 receptor subtype responsible for this effect belongs to the same subtype (NK 2A) previously identified in the rabbit pulmonary artery and guinea-pig bronchi.

Contractile effects of substance P and other tachykinins on the mouse isolated distal colon

1. Substance P (SP), physalaemin, eledoisin and kassinin induced concentration-related contractions of the longitudinal muscle of the mouse distal colon. The responses were not antagonized by atropine (1.5 x 10(-7) M), mepyramine (2.5 x 10(-7) M), methysergide (5 x 10(-7) M), timolol (10(-6) M), phentolamine (10(-6) M) or naloxone (4 x 10(-7) M). They were enhanced by tetrodotoxin (TTX, 1.5 x 10(-7) M). These observations indicate that the contractile responses to the tachykinins result from a direct activation of smooth muscle cells. 2. The contractile activity provoked by SP and physalaemin was inhibited by nifedipine (a Ca2+-entry blocker) and was abolished in Ca2+-free EGTA solution. Such data suggest that the myogenic effects of SP and physalaemin are mainly dependent on their ability to promote Ca2+ influx. 3. Eledoisin and kassinin evoked a contractile response in the absence of external Ca2+ and their myogenic activity was, to some extent, resistant to the inhibitory effect of nifedipine. This may indicate that an additional process, probably the release of an intracellularly bound Ca2+ store, participates in the mechanism by which eledoisin and kassinin contract the mouse distal colon. 4. After desensitization of the mouse distal colon to SP, the contractile activity provoked by SP or physalaemin was totally abolished whilst the responses evoked by eledoisin and kassinin were barely affected. These observations and other experimental findings indirectly support the assumption that the mouse distal colon could possess different tachykinin-binding sites.

Effects of Human Calcitonin Gene-Related Peptide and Substance P on Human Intracervical Arteries

The contractile effects of substance P and human calcitonin gene-related peptide (human CGRP) on isolated human intracervical arteries were studied. Human cervical tissue specimens were excised after hysterectomy at various phases of the menstrual cycle (n = 14) and small intracervical arteries were dissected free by microtechnique. Ring preparations of the vessels were prepared and mounted in organ baths, and isometric circular tension was recorded. Neither compound affected resting tension. Both peptides showed potent relaxing effects on vessels precontracted by noradrenaline 10(-5) M. Substance P exhibited the higher potency, while human CGRP showed the higher efficacy. The relaxing effects of the two compounds were unaffected by pretreatment with indomethacin 10(-6) M, propranolol 10(-6) M and atropine 10(-6) M. The results support a role for the two peptides in the regulation of cervical blood flow.

Contractile effects of substance P and neurokinin A on the rat stomach in vivo and in vitro

Substance P and neurokinin A (substance K) were infused into the coeliac artery of anaesthetized rats at doses of 0.06-20 nmol min-1. Both tachykinins caused contractions of the stomach, the threshold dose of neurokinin A being 10 times lower than of substance P. The dose-response curve for substance P was flatter than that for neurokinin A. On circular muscle strips from the rat gastric corpus in vitro, the dose-response curves for both tachykinins were parallel, neurokinin A being 10 times more potent than substance P. The contractions in response to 10 microM neurokinin A and to 30 microM substance P were 58 and 54%, respectively, of the maximal contraction to bethanechol (1 mM). The effect of substance P was reduced by atropine both in vivo and in vitro. In vitro, the contractions to substance P were also reduced by tetrodotoxin but left unaffected by methysergide. The action of neurokinin A was not affected by these drugs. It is concluded that neurokinin A contracts rat stomach by a direct action on the circular smooth muscle, whereas the action of substance P is mediated, at least in part, by cholinergic interneurones.

Antagonist discrimination between subtypes of tachykinin receptors in the guinea-pig ileum

The effects of substance P and eledoisin on spontaneous and electrically-evoked release of [3H]acetylcholine, and on smooth muscle were studied in the guinea-pig myenteric plexus-longitudinal muscle preparation preloaded with [3H]choline. Substance P and eledoisin caused transient increases in spontaneous release of [3H]-acetylcholine and in longitudinal muscle tone. Both tachykinins were equipotent in contracting the muscle, but eledoisin was more potent than substance P in eliciting [3H]acetylcholine release. The release caused by substance P was enhanced in the presence of naloxone and scopolamine which suggests that the release is modulated through opioid and muscarinic receptors. Substance P and eledoisin inhibited the release of [3H]acetylcholine evoked by electrical stimulation at 0.1 Hz. The inhibition was not due to an activation of alpha-adrenoceptors, histamine or opioid receptors. The substance P antagonists (D-Pro2, D-Trp7,9)SP (10 and 30 microM) and (Arg5, D-Trp7,9, Nle11)SP5-11 (1 and 10 microM) competitively antagonized both the contractile effects of substance P and eledoisin, and the inhibition by the tachykinins of the electrically-evoked release of [3H]acetylcholine. The increase in spontaneous [3H]acetylcholine release elicited by substance P and eledoisin was not prevented by the substance P antagonists. The results suggest that the neuronal receptor whose activation causes inhibition of acetylcholine release and the smooth muscle receptor correspond to the SP-P type, whereas the neuronal receptor mediating an increase in spontaneous acetylcholine release is of the SP-E type. The two antagonists, (D-Pro2, D-Trp7,9)SP and (Arg5, D-Trp7,9, Nle11)SP5-11, selectively block only the SP-P receptor.

Pharmacological analysis of the mechanism of action for colonic contraction induced by neurotensin, substance P and methionine‐enkephalin

Infusion of neurotensin, substance P and methionine-enkephalin induces colonic contraction in the cat. The present study was performed to investigate the effect of various pharmacological blocking agents on colonic contraction evoked by these peptides infused by the i.a. or i.v. route. The contractions caused by infusions of neurotensin were blocked by tetrodotoxin (1 micrograms kg-1 i.a.), hexamethionium (10 mg kg-1 i.v.), atropine (0.1 mg kg-1 i.v.) or somatostatin (100 pmol min-1 i.a.), but not by haloperidol, methysergide, mepyramine, cimetidine or naloxone. The contractile effect of substance P on the colon was abolished by the substance P receptor antagonist (D-Arg1, D-Pro2, D-Trp7,9, Leu11)-substance P (70 nmol min-1 i.a.). No other blockers used, such as tetrodotoxin, hexamethonium, atropine, mepyramine, cimetidine, methysergide, naloxone or somatostatin inhibited the response to substance P. Methionine-enkephalin produced a colonic contraction that was completely blocked by naloxone (1 mg kg-1 i.a.). Both atropine (0.1 mg kg-1 i.v.) and somatostatin (100 pmol min-1 i.a.) reduced the contractile response. However, tetrodotoxin, hexamethonium, mepyramine, cimetidine and methysergide did not affect the response to methionine-enkephalin. All adrenergic blockers tested, that is, guanethidine, propranolol and phentolamine, increased the contractile responses to the peptides. The results indicate that the colonic contraction induced by neurotensin is mediated via nervous cholinergic pathways. Substance P induces colonic contraction, probably by a direct effect on smooth muscle substance P receptors. Methionine-enkephalin induces colonic contraction which could be blocked by naloxone. However, a cholinergic or peptidergic link may also be involved in the response to methionine-enkephalin.

Concentrations and contractile effects of substance P in the human ampullary‐isthmic junction

From 20 women undergoing hysterectomy, strip preparations were isolated from the outer, longitudinal and the inner, circular smooth muscle layer of the ampullary-isthmic junction (AIJ), together with small arterial segments dissected as ring preparations from the root of the mesosalpinx. The specimens were mounted in organ baths and isometric tension was recorded. In addition, tissue concentrations of substance P (SP) in the ampulla, AIJ and utero-tubal junction were determined by radioimmunoassay. Tissue concentrations of SP expressed as pmol X g tissue-1 (wet weight, +/- SE) amounted to 3.09 +/- 1.40 in the utero-tubal junction, 1.08 +/- 0.299 in the AIJ and 0.742 +/- 0.299 in the ampulla. In strips of circular muscle, SP at concentrations of 10(-7) -3 X 10(-6) mol X l-1 elicited a combined phasic and tonic response and in longitudinal muscle a mainly tonic contraction was produced. In both tissues, contractions elicited by SP were rapidly abolished in calcium-free medium. Nifedipine abolished the phasic contraction elicited in circular muscle by SP while the tonic response was resistant. The contraction in longitudinal muscle was reduced by 20-30%. Vasoactive intestinal polypeptide (VIP) decreased tension in preparations contracted by SP, prostaglandin F2 alpha and K+-depolarization (124 mmol X l(-1). In unstimulated oviductal arterial preparations, SP had no effect, while the peptide induced a transient relaxation of noradrenaline contracted preparations, and slightly decreased tension of K+-depolarized vessels. The results suggest that SP may be involved in the control of motility of the human AIJ.

On the mechanism of contraction and desensitization induced by substance P in the intestinal muscle of the guinea-pig.

The contractile effect of substance P on the longitudinal muscle of the isolated guinea-pig small intestine and the desensitization of the muscle which occurs on prolonged exposure to the peptide have been investigated. All experiments were performed in the presence of atropine. The response to a substance P concentration which produced a nearly maximal effect was not sustained but faded rapidly. It was found that not elimination of substance P from the bath, but desensitization of the muscle to substance P was the main cause for the fading of contraction. Desensitization of the muscle to substance P only developed if the muscle was exposed to the peptide for a certain time. The degree of and the time needed for recovery from desensitization were directly related to concentration of substance P and contact time. Tetraethylammonium (3 mM), which reduces the membrane conductance for K+, enhanced the potency of substance P in contracting the muscle and reduced the fading of contraction. Noradrenaline (295 nM), which increases the K+ conductance, produced opposite effects. Lowering the extracellular Ca2+ concentration to one-tenth decreased the potency of substance P in contracting the muscle, accelerated the fading of contraction, and reduced the ability of the muscle to respond to a second addition of substance P after the response to the first addition had faded away. Concentrations of substance P (22 nM) and tetraethylammonium (30 mM), which produced nearly maximal contractions, slightly enhanced the efflux of 86Rb from pre-loaded muscle strips. Both substances, however, caused a sustained reduction of 86Rb efflux from strips depolarized by high [K+], the effect of substance P being smaller than that of tetraethylammonium. The effect of substance P and tetraethylammonium on 86Rb efflux appeared independent of the extracellular [Ca2+]. On exposure of the muscle to substance P (22 nM) for 8 min the intracellular uptake of 45Ca was first decreased and then increased while the 45Ca influx was instantly enhanced by tetraethylammonium (30 mM) or K+ (108 mM). The delayed increase in 45Ca influx caused by substance P was also observed in muscle strips depolarized with high [K+].(ABSTRACT TRUNCATED AT 400 WORDS)

Contractile effect of substance P on the canine urinary bladder in vivo

AbstractRecent immunohistochemical studies have demonstrated a supply of polypeptides in neurons in many peripheral tissues including the lower urinary tract. The presence of substance P (SP) in the urinary bladder have been documented. In previous in vitro studies on isolated bladder muscle strips SP was found to have a contractory effect. In the present in vivo study intravesical pressure and arterial pressure were recorded following intraarterial administration of SP into six adult female dogs. Following administration of SP in doses of 0.1–0.75 μg/kg body weight (BW) no effect on intravesical pressure and a short‐lasting decrease in arterial blood pressure were recorded. Following SP in doses of 1–10 μg/kg BW an immediate and moderate increase in intravesical pressure and marked and longlasting decrease in intraarterial blood pressure were recorded. On the basis of the previous in vitro and immunohistochemical studies and the present in vivo study, the role of SP as a modulator of tone and motility of the urinary bladder should be considered.

Contractile effects of substance P, substance P fragments, and tachykinin peptides on the rabbit external jugular vein in vitro

Contractile effects of substance P, substance P fragments, and tachykinin peptides on the rabbit external jugular vein in vitro

Different contractile effects of substance P on the intestine of mammals.

The contractile effect of substance P was examined on the longitudinal muscle of isolated sections of the gut of cat, guinea-pig, rabbit, and rat. Substance P caused contraction of all intestinal regions investigated, but there were marked qualitative and quantitative differences in the contractile responses to substance P. Low concentrations of substance P that did not cause tonic contraction (0.22--2.2 nM), increased the phasic longitudinal contractions observed in the ileum of cat, pig, and rabbit. Higher concentrations induced a tonic longitudinal contraction of the ileum, which in the cat, pig and rat was accompanied by facilitation and in the rabbit by inhibition of the phasic contractions. While in the ileum of guinea-pig and rabbit the maximal longitudinal contraction induced by substance P was equal to the maximal effect of acetylcholine, the maximal response to substance P was only about 50% of that to acetylcholine in the ileum of cat, pig, and rat. The jejunum, ileum and colon of the rabbit responded to substance P and acetylcholine was similar maximal contractions, but the jejunum appeared to be most and the ileum least sensitive to substance P. The results suggest qualitatively and quantitatively different roles of substance P in the intestinal motility of different mammals.