Role of vascular alpha 2-adrenoceptors as targets for circulating catecholamines in the maintenance of blood pressure in anaesthetised spontaneously hypertensive rats.
We examined the blood pressure-lowering effects of the alpha 2-adrenoceptor antagonist rauwolscine in anaesthetised spontaneously hypertensive rats (SHR). In the absence of prior drug, rauwolscine (1-10 mg kg-1) produced dose-dependent falls in diastolic blood pressure (DBP). In the presence of prazosin (1 mg kg-1) to eliminate alpha 1-adrenoceptor-mediated responses, rauwolscine (0.1-1 mg kg-1) lowered DBP in unoperated and sham-operated animals but not in adrenal demedullated animals. Hence, we were able to demonstrate that alpha 2-adrenoceptors are involved in the control of blood pressure in intact anaesthetised SHR but not following adrenal demedullation, suggesting that circulating catecholamines are responsible for these alpha 2-adrenoceptor-mediated pressor effects.
Sawyer
R
R
Warnock
P
P
Docherty
J R
JR
D000313:Adrenal Medulla / Q000502:physiology; D000758:Anesthesia; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002395:Catecholamines / Q000502:physiology*; D006830:Hydralazine / Q000494:pharmacology; D006973:Hypertension / Q000503:physiopathology*; D008297:Male; D011224:Prazosin / Q000494:pharmacology; D051381:Rats; D011918:Rats, Inbred SHR; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*; D014991:Xylazine / Q000494:pharmacology; D015016:Yohimbine / Q000494:pharmacology
D002395:Catecholamines; D011942:Receptors, Adrenergic, alpha; D006830:Hydralazine; D014991:Xylazine; D015016:Yohimbine; D011224:Prazosin