Dopamine In Perfusates Research Articles

Excretion and metabolism of dopa and dopamine by isolated perfused rat kidney.

The renal metabolism and handling of dopa and dopamine were studied with the use of the isolated perfused rat kidney to elucidate the source of urinary dopamine. Dopa added to the perfusate was rapidly metabolized, and a significant amount of urinary dopamine excretion was observed, whereas dopa was not detected in the urine. When the perfusate dopa concentration was near the plasma dopa concentration in normal rats, urinary dopamine excretion was comparable with physiological values. Carbidopa, a dopa decarboxylase blocker, added to the perfusate markedly reduced the urinary excretion of dopamine. When the physiological concentration of dopamine was added to the medium, the perfusate dopamine rapidly decreased and urinary dopamine excretion was much less than that seen in normal rats. In studies with nonfiltering kidneys, a marked decrease of dopa and slight increase of dopamine in the perfusate were observed. It is suggested that the process of glomerular filtration and tubular reuptake of dopa is not essential for renal dopamine formation. These data indicate that urinary free dopamine is mainly derived from plasma dopa, which is converted by dopa decarboxylase in the kidney.

Conjugates of dopamine and serotonin in ventriculocisternal perfusates of the cat.

The in vivo formation of acid-hydrolyzable conjugates of dopamine and of serotonin (presumably dopamine-O-sulfate and serotonin-O-sulfate) in ventriculocisternal perfusions of the cat is described. Small amounts of these amine conjugates were detected under quiescent conditions and during evoked release of the parent amines. The amounts of conjugated dopamine in perfusate were increased during and immediately after the period in which release of dopamine was evoked, but were not affected by inhibition of monoamine oxidase. In contrast, the efflux of serotonin conjugate during the evoked release of serotonin was not increased unless monoamine oxidase was inhibited. The data suggest that conjugation of amines in the CNS may be of functional importance in their disposition either under conditions of augmented release or during inhibition of oxidative deamination.

Neuronal response to dopamine in rat neostriatum A push-pull perfusion study

In light of the sustained controversy surrounding the effects of dopamine (DA) in the striatum, this investigation sought to identify the pharmacological effects of locally infused DA on neuronal function. A push-pull perfusion technique of discrete drug application was employed, with single unit extracellular recording, in attempts to establish a clear dose-effect relationship between DA and neuronal activity. Locally perfused DA was found to modulate the discharge rate of striatal neurons over the entire test range (10 −7-10 −10 M). Varied responses were detected, with 7% of the units exhibiting facilitation and 55% depression; 11% of these displayed biphasic excitation/inhibition. Taking everything into consideration, no strict dose-response relationship was evident for excitation and depression. However, the degree of depression appeared to be directly related to the concentration of DA which was perfused, especially when considered as a function of the initial discharge rate. Upon repeated perfusion of DA, the neuronal responsiveness progressively declined. These observations are consistent with data derived from extracellular, iontophoretic studies on the same neuronal population.

Association nitroglycérine et remplissage vasculaire dans la chirurgie de l'aorte abdominale

Haemodynamic investigations were performed in nine patients during aortic surgery for Leriche's syndrome. Most of these patients had ischaemic heart disease without cardiac failure. Fluid loading was carried out before and during aortic clamping. It was controlled according to the optimal wedge pulmonary pressure determined the day before surgery. Only six of the nine patients received nitroglycerin (NTG : 0.2 μg · kg −1 · min −1) throughout the operation. Before clamping, cardiac index was improved in patients treated with NTG. During clamping, the patients not treated with NTG showed a drop in cardiac index, an increase in peripheral resistance and in left cardiac work. After declamping, there were no haemodynamic differences between the two groups. Two patients not treated with NTG developed azotaemia postoperatively; one patient developed cardiac failure requiring a dopamine perfusion during surgery. In this series, the association of optimal volume loading with a peroperative perfusion of 0.2 μg · kg −1 · min −1 NTG gave a good haemodynamic stability.

Cyclic nucleotides in the rat neostriatum: Push-pull perfusion studies

A push-pull perfusion technique was employed for in vivo study of adenosine 3',5'-monophosphate (cAMP) and guanosine 3',5'-monophosphate (cGMP) in the rat caudate nucleus. Addition of dopamine to the perfusion fluid elicited dose-dependent increases of both cAMP and cGMP perfusate concentrations. In separate experiments, it was found that pretreatment of animals with the dopamine antagonist, pimozide, significantly depressed both nucleotide responses to dopamine perfusion over the dose range studied. Mechanistic interpretations of the observations are considered. The push-pull perfusion technique appears to provide an extremely useful means of examining extracellular cyclic nucleotide levels in a discrete brain region, in vivo, under dynamic conditions.

Evidence for identified dopamine motor neurons to the gill of Aplysia

Dopamine (DA) is present in the gill of Aplysia in considerable quantity. We have investigated the possibility that DA may be an excitatory neuromuscular transmitter. Perfusion of DA through the gill elicits contraction of the same muscles as are activated by the identified motor neurons L 7 and L 9. The cholinergic motor neuron LDG 1 activates different muscles. The contractions induced by DA and three L 9 neurons but not that of L 7 are blocked by ergometrine. These results are consistent with the possibility that the neurons L 9, L 9-A and L 9-P are dopaminergic motor neurons.

Human behavioural arousal induced by dopamine.

British Journal of Clinical PharmacologyVolume 6, Issue 4 p. 369-370 Free Access Human behavioural arousal induced by dopamine. DJ Boullin, DJ BoullinSearch for more papers by this authorCB Adams, CB AdamsSearch for more papers by this authorGH Du Boulay, GH Du BoulaySearch for more papers by this author DJ Boullin, DJ BoullinSearch for more papers by this authorCB Adams, CB AdamsSearch for more papers by this authorGH Du Boulay, GH Du BoulaySearch for more papers by this author First published: October 1978 https://doi.org/10.1111/j.1365-2125.1978.tb00866.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. References ADAMS, C.B.T., LOACH, A.B. & O'LAOIRE, S.A. (1976). Intracranial aneurysms: analysis of results of micronerusurgery Br. med. J., 2, 607– 609. ALLCOCK, J.M. & DRAKE, C.G. (1965). Ruptured intracranial aneurysms The role of arterial spasm. J. Neurosurg., 22, 21– 29. BLASCHKO, H. & CHRUSCHIEL, T.L. (1960). The decarboxylation of amino acids related to tyrosine and their awakening action in reserpine-treated mice. J. Physiol., 151, 272– 283. BOULLIN, D.J., ADAMS, C.B.T., MOHAN, J., GREEN, A.R., HUNT, T.M., DU BOULAY, G.H. & ROGERS, A.T. (1977). Effects of intracranial dopamine perfusion: behavioural arousal and reversal of cerebral arterial spasm following surgery for clipping of ruptured cerebral aneurysms. Proc. roy. Soc. Med., 70, Suppl. 2, 55– 70. VON ESSEN, C. (1972). Effects of dopamine, noradrenaline and 5-hydroxytryptamine of the cerebral blood flow in the dog. J. Pharm. Pharmac., 24, 668. VON ESSEN, C. (1974). Effects of dopamine on the cerebral blood flow in the dog. Acta Neurol. Scand., 50, 39– 52. GREEN, A.R. & KELLY, P.H. (1976). Evidence concerning the involvement of 5-hydroxytryptamine in the locomotor activity produced by amphetamine or tranylcypromine plus L-dopa. Br. J. Pharmac., 57, 141– 147. MACPHERSON, P. & GRAHAM, D.I. (1978). Correlation between angiographic findings and the ischaemia of head injury. J. Neurol. Neurosurg. Psychiat., 41, 122– 127. Volume6, Issue4October 1978Pages 369-370 ReferencesRelatedInformation

Elevation of adenosine 3′,5′-monophosphate in the perfusate of rat kidney after addition of dopamine

Dopamine (10-4 M) and vasopressin (1 mU/ml) were found to increase the level of cyclic AMP in the perfusate of rat kidney. There were some differences in the mode of action of these two drugs. Firstly, the effect of dopamine, but not of vasopressin, was completely antagonized by spiroperidol. Secondly, the maximal response was attained within 1 min after dopamine perfusion, but 8 min after vasopressin perfusion. These results suggest that a specific dopamine receptor which acts to increase the concentration of cyclic AMP is located in the vascular tissue of rat kidney.

Effects of Intracranial Dopamine Perfusion: Behavioural Arousal and Reversal of Cerebral Arterial Spasm following Surgery for Clipping of Ruptured Cerebral Aneurysms

Effects of Intracranial Dopamine Perfusion: Behavioural Arousal and Reversal of Cerebral Arterial Spasm following Surgery for Clipping of Ruptured Cerebral Aneurysms

Effect of dopamine on renin secretion in the anesthetized dog

Intrarenal perfusion of dopamine (6 μg/kg/min for 10 min) causes a significant increase of renin secretion, together with a significant increase in renal blood flow. This renin hypersecretion is not accompanied by any significant alteration in renal perfusion pressure, kalemia or natriuresis. The role of intrarenal dopaminergic receptors has been studied: (a) Haloperidol (intrarenal perfusion of 50 μg/kg/min for 20 min) suppresses the renal vasodilation and renin hypersecretion induced by dopamine. (b) Propranolol (intrarenal perfusion of 1 mg/kg in 15 min, then of 4 mg/kg/hr) alters neither the renal vasodilation nor the renin hypersecretion induced by dopamine. These observations support the assumption that the dopaminergic receptors are brought into play in the two renal responses to dopamine studied by us.