Effect of alpha 1-adrenoceptor blockade on blood pressure and iliac vascular resistance in normotensive and Goldblatt hypertensive dogs; influence of dietary salt and DOCA-salt.
Instrumented normotensive and two-kidney, one clip Goldblatt hypertensive dogs were placed on normal salt, high salt and DOCA-salt regimens and the effect on mean arterial blood pressure (MAP) and iliac vascular resistance (IVR) determined. High salt and DOCA-salt did not alter these variables in the Goldblatt hypertensive group. DOCA-salt increased MAP in the normotensives by 12 mmHg; however, IVR was not significantly increased by this treatment. In order to determine the degree of sympathetic tone in the iliac vascular bed, the change in IVR evoked by the alpha 1-adrenoceptor antagonists, urapidil and prazosin, was assessed. There were similar reductions in MAP and IVR after alpha 1-blockade in both groups of dogs, regardless of the salt regimen. However, urapidil caused a greater decrease in MAP in the normotensives than in the hypertensives. Captopril administration after alpha 1-blockade caused further reductions in MAP and IVR in the hypertensives, and in the MAP of the normotensive dogs on normal or high salt, indicating that the renin-angiotensin system maintained blood pressure in these groups. These results suggest that sympathetic tone is not increased by high salt- or DOCA-salt in normotensive or Goldblatt hypertensive dogs for the 8-11 day duration of these treatments.
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002216:Captopril / Q000494:pharmacology; D003900:Desoxycorticosterone / Q000494:pharmacology; D004285:Dogs; D005260:Female; D006978:Hypertension, Renovascular / Q000503:physiopathology*; D007083:Iliac Artery / Q000187:drug effects; D008297:Male; D010656:Phenylephrine / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D012039:Regional Blood Flow / Q000187:drug effects; D012982:Sodium, Dietary / Q000494:pharmacology*; D014655:Vascular Resistance / Q000187:drug effects*
D000317:Adrenergic alpha-Antagonists; D010879:Piperazines; D012982:Sodium, Dietary; D010656:Phenylephrine; D003900:Desoxycorticosterone; D002216:Captopril; C015568:urapidil; D011224:Prazosin