Modulation of vasopressin antidiuretic action by alpha 2-adrenoceptors is species specific.
There is evidence in the rat that stimulation of renal alpha 2-adrenoceptors modulates vasopressin antidiuretic action and vasopressin-stimulated adenylate cyclase activity. In the present study, we tested the ability of various alpha 2-adrenoceptor agonists to antagonize vasopressin-induced antidiuresis in the conscious hydrated dog and to inhibit vasopressin-induced adenosine 3',5'-cyclic monophosphate (cAMP) generation in rat and dog cortical collecting tubules. Vasopressin infusion (0.01 ng.kg-1.min-1) in five dogs resulted in a decrease in free water clearance from 2.90 +/- 0.42 to -0.34 +/- 0.08 ml/min. The vasopressin receptor antagonist SKF 105494 inhibited this response. Administration of norepinephrine (0.5 microgram.kg-1.min-1) or clonidine (20 micrograms/kg), however, failed to alter the vasopressin-induced antidiuresis. In vitro studies demonstrated that epinephrine caused a dose-dependent reduction in vasopressin-stimulated cAMP levels in cortical collecting tubules from the rat (50% effective concentration 32 nM) but not from the dog. The data indicate that there is a species difference in alpha 2-adrenoceptor modulation of vasopressin action.
Brooks
D P
DP
SmithKline Beecham Pharmaceuticals, King of Prussia, Pennsylvania 19406-0939.
Gellai
M
M
DePalma
P D
PD
Edwards
R M
RM
D000262:Adenylyl Cyclases / Q000378:metabolism; D057911:Angiotensin Receptor Antagonists; D000818:Animals; D001127:Arginine Vasopressin / Q000031:analogs & derivatives / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D003000:Clonidine / Q000494:pharmacology*; D000242:Cyclic AMP / Q000378:metabolism; D004231:Diuresis / Q000187:drug effects; D004285:Dogs; D004837:Epinephrine / Q000494:pharmacology*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D066298:In Vitro Techniques; D007668:Kidney / Q000187:drug effects / Q000502:physiology*; D007672:Kidney Cortex / Q000187:drug effects / Q000502:physiology; D007685:Kidney Tubules, Collecting / Q000187:drug effects / Q000502:physiology; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology*; D011433:Propranolol / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects / Q000502:physiology*; D011945:Receptors, Angiotensin / Q000502:physiology; D017483:Receptors, Vasopressin; D013045:Species Specificity; D014667:Vasopressins / Q000037:antagonists & inhibitors
D057911:Angiotensin Receptor Antagonists; D011942:Receptors, Adrenergic, alpha; D011945:Receptors, Angiotensin; D017483:Receptors, Vasopressin; C055736:SK&F 105494; D014667:Vasopressins; D001127:Arginine Vasopressin; D011433:Propranolol; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; D003000:Clonidine; D009638:Norepinephrine; D004837:Epinephrine