EFFECTS OF IMPROMIDINE, A SPECIFIC H2-RECEPTOR AGONIST AND 2-(2-PYRIDYL)-ETHYLAMINE, AN H1-RECEPTOR AGONIST, ON STIMULATION-INDUCED RELEASE OF [3H]-NORADRENALINE IN GUINEA-PIG ISOLATED ATRIA
Autor: | Michael J. Rand, David F. Story, H. K. Wong-Dusting |
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Rok vydání: | 1982 |
Předmět: |
Male
Agonist medicine.medical_specialty Sympathetic Nervous System Pyridines medicine.drug_class Guinea Pigs Mepyramine Histamine H1 receptor In Vitro Techniques Pharmacology Guanidines Norepinephrine chemistry.chemical_compound Histamine receptor Impromidine Histamine H2 receptor Heart Rate Internal medicine medicine Animals Receptors Histamine H2 Receptors Histamine H1 Cimetidine Phentolamine Myocardium Imidazoles Heart Myocardial Contraction Electric Stimulation Endocrinology chemistry Receptors Histamine Female Histamine Research Article medicine.drug |
Zdroj: | British Journal of Pharmacology. 76:305-311 |
ISSN: | 0007-1188 |
DOI: | 10.1111/j.1476-5381.1982.tb09221.x |
Popis: | 1 The specific histamine H2-receptor agonist, impromidine (3-100 nmol/l), increased the rate and force of beating of guinea-pig isolated atria. These effects were blocked by the H2-receptor antagonist, cimetidine (30 mumol/l), but not by the H1-receptor antagonist, mepyramine (0.1 mumol/l). 2 In atria that had previously been incubated in [3H]-noradrenaline, impromidine (3-100 nmol/l) had no effect on the resting efflux of radioactivity, but concentrations of 50 and 100 nmol/l significantly increased the efflux induced by electrical stimulation (2 Hz for 10 s) of the intramural sympathetic nerves by approximately 38%; lower concentrations (3, 10 and 25 nmol/l) had no effect. 3 The effect of impromidine in enhancing stimulation-induced efflux of radioactivity was abolished by cimetidine (30 mumol/l) and by mepyramine (0.1 mumol/l). It was unaffected by the alpha-adrenoceptor antagonist, phentolamine (30 mumol/l). 4 Impromidine produced some inhibition of the uptake of [3H]-noradrenaline, but this did not account for the enhancement of the stimulation-induced efflux of radioactivity, since impromidine (50 mumol/l) still increased release in the presence of cocaine (30 mumol/l). 5 The specific H1-receptor agonist, 2-(2-pyridyl)-ethylamine (10-100 mumol/l), increased both the resting and stimulation-induced efflux of radioactivity. These effects were not blocked by mepyramine (0.1 mumol/l) or the beta-adrenoceptor antagonist, metoprolol (0.1 mumol/l). 6 The prejunctional inhibitory histamine receptors in guniea-pig atria are not classifiable into H1- or H2-type by the use of relatively specific postjunctional histamine H1- or H2-receptor agonists and antagonists. |
Databáze: | OpenAIRE |
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