Year: 1969
Type: article
Abstract: Norepinephrine synthesis was determined in the heart and adrenals of rabbits made hypertensive by complete denervation of the carotid sinuses and aortic arch.There was a 24% reduction of norepinephrine concentration in the left ventricle 3 weeks after denervation, despite evidence of enhanced synthesis as determined by three methods: (1) an 18% increase in apparent synthesis rates (from 0.76 to 0.90 m^imoles/g/hour) calculated from norepinephrine turnover rates after infusion of DL-norepinephrine-3 H; (2) a 124% increase in synthesis rates (from 2.1 to 4.7 m^moles/g/hour) estimated from the incorporation of label from infused tyrosine-3 H; (3) a 50% increase (from 4.0 to 6.0 mju.moles/g/hour) in the activity of the regulatory enzyme tyrosine hydroxylase.Additionally, in the denervated rabbits there was a 43% reduction in the amount of epinephrine in the adrenal gland 2 days after denervation and a return to normal values at 3 weeks.Adrenal tyrosine hydroxylase, phenylethanolamine-N-methyl transferase, and the incorporation of label from tyrosine-8 !! into epinephrine were increased at 3 weeks.A smaller number of hypertensive rabbits studied at 2 days showed a reduction in left ventricular norepinephrine concentration.Catecholamine reductions, due only in part to dilutional hypertrophy, may be related to increased utilization and may serve to enhance synthesis of the neurotransmitter and maintain the increase in blood pressure. ADDITIONAL KEY WORDS biosynthesis baroreceptor denervation catecholamines carotid sinus aortic pressure receptors phenylethanolamine-N-methyl transferase tyrosine hydroxylase hypertension• Biochemical evidence of altered sympathetic nerve function has been reported in essential hypertension (1, 2).Defective neurotransmitter storage has also been demonstrated in a salt-loaded, DOCA-treated, uninephrectomized animal model with experimental arterial hypertension (3).However, the pathophysiologic conditions induced in that model are not present in essential hyperten-
Source: Circulation Research
Authors: V. DEQUATTRO, T. NAGATSU, R. MARONDE, N. ALEXANDER
Institution: University of Southern California
Language: English
Subfield: Cardiology and Cardiovascular Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: bronze
OpenAlex ID: W2155607773