Abstract

In pentobarbital-anesthetized dogs with decentralized adrenal glands, sinoaortic baroreceptor deafferentation produced an increase in mean aortic blood pressure which reached a maximum (42 +/- 5 mm Hg, n = 6) within 5 min and then waned entirely within the subsequent 25 min. In contrast, in sham-operated dogs, the maximal pressor response due to deafferentation was of greater magnitude (63 +/- 6 mm Hg, n = 8) and of much longer duration (44 +/- 4 mm Hg, 60 min after deafferentation). Heart rate was only augmented slightly in both preparations. A marked elevation of epinephrine plasma concentration occurred 5 min after deafferentation and the magnitude of this effect was 8 times greater in dogs with innervated than denervated adrenal glands. Norepinephrine plasma concentration increased moderately and similarly in the two preparations. Administration of pergolide (30.0 micrograms/kg i.v.) 15 min before undertaking the deafferentation procedure induced a small, short-lasting increase in blood pressure and a small fall in heart rate in dogs in which the innervation to the adrenal glands was left either intact (sham-operated) or removed surgically. In dogs with adrenal gland denervated, pergolide blocked entirely the pressor response and the small elevation in plasma concentration of catecholamines evoked by sinoaortic deafferentation in the matched, saline-pretreated group. However, in sham-operated dogs (intact adrenal innervation), pergolide reduced partially (by 41%) the increase in blood pressure and plasma epinephrine concentration caused by deafferentation. The decrease in heart rate, produced by pergolide, was abolished by deafferentation in sham-operated and adrenal decentralized dogs.(ABSTRACT TRUNCATED AT 250 WORDS)