Paradoxical effects of endothelin on cardiovascular noradrenergic neurotransmission.
1. Pre- and postjunctional effects of endothelin (1-10 nmol/L) have been studied in the rabbit isolated ear artery and in rat isolated atria. 2. Endothelin produced concentration-dependent increases in arterial perfusion pressure, and had positive chronotropic and inotropic effects in rat atria. 3. Vasoconstrictor responses of the arteries to sympathetic nerve stimulation were reduced by 1 nmol/L endothelin and abolished by 10 nmol/L endothelin. In rat atria, the chronotropic responses to nerve stimulation were markedly reduced by 10 nmol/L endothelin. 4. In rabbit ear artery, vasoconstrictor responses to noradrenaline were enhanced by 1 nmol/L endothelin, but were reduced by 10 nmol/L endothelin. In rat atria, endothelin reduced the chronotropic response to isoprenaline. 5. Endothelin (10 nmol/L) increased the stimulation-induced release of radioactivity in arteries and atria labelled with [3H]-noradrenaline by 91% and 23%, respectively. 6. The pre- and postjunctional effects of endothelin persisted in both arterial and atrial preparations for at least 30 min after its removal.
Wong-Dusting
H K
HK
Department of Pharmacology, University of Melbourne, Victoria, Australia.
Reid
J J
JJ
Rand
M J
MJ
D000818:Animals; D001158:Arteries / Q000187:drug effects / Q000294:innervation / Q000502:physiology; D002320:Cardiovascular Physiological Phenomena; D002319:Cardiovascular System / Q000187:drug effects / Q000294:innervation*; D004558:Electric Stimulation; D016232:Endothelins; D006321:Heart / Q000187:drug effects / Q000294:innervation / Q000502:physiology; D066298:In Vitro Techniques; D009638:Norepinephrine / Q000502:physiology*; D010455:Peptides / Q000494:pharmacology*; D011817:Rabbits; D051381:Rats; D013564:Sympathetic Nervous System / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects*
D016232:Endothelins; D010455:Peptides; D009638:Norepinephrine