alpha1-Adrenoceptor subtypes mediating antinatriuresis in Wistar and stroke-prone spontaneously hypertensive rats.
This study examined the alpha1-adrenoceptor subtypes involved in mediating adrenergically induced Na+ reabsorption in the kidney of pentobarbitone anaesthetised Wistar and stroke-prone spontaneously hypertensive rats (SHRSP). Close renal-arterial phenylephrine (50-100 mu g kg-1 h-1) administration in Wistars, with regulated renal perfusion pressure, caused small reductions in renal haemodynamics but large reductions, of 35%, 64% and 57% (all P < 0.05), in urine volume, absolute and fractional Na+ excretions. The magnitude of these excretory responses to phenylephrine were similar in the presence of the alpha1B-adrenoceptor alkylating agent, chloroethylclonidine (10 mu g kg-1 h-1), but were blocked during administration of the alpha1A-adrenoceptor antagonist, 5-methylurapidil (10 mu g kg-1 h-1). Phenylephrine infusion in the stroke-prone spontaneously hypertensive rats caused changes in renal haemodynamics and fluid excretion of comparable magnitude to that achieved in Wistars which was blocked by 5-methylurapidil but not chloroethylclonidine. These observations suggest that in Wistar and stroke-prone spontaneously hypertensive rats the adrenergically induced Na+ reabsorptive responses are mediated by alpha1A-adrenoceptors.
Sattar
M A
MA
Department of Physiology, The Medical School, Birmingham, UK.
Johns
E J
EJ
D000818:Animals; D003000:Clonidine / Q000031:analogs & derivatives / Q000494:pharmacology; D004231:Diuresis; D006973:Hypertension / Q000378:metabolism*; D008297:Male; D009318:Natriuresis; D010656:Phenylephrine / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D051381:Rats; D011918:Rats, Inbred SHR; D017208:Rats, Wistar; D018340:Receptors, Adrenergic, alpha-1 / Q000502:physiology*
D010879:Piperazines; D018340:Receptors, Adrenergic, alpha-1; C057446:5-methylurapidil; D010656:Phenylephrine; C051731:chlorethylclonidine; D003000:Clonidine