neuropeptide-y and Hypertension--Renovascular

Nanomoles of neuropeptide Y (NPY) and noradrenaline (NA), administered i.v. to pentobarbital-anesthetized rats, caused nearly equipotent dose-dependent pressor responses in normotensive rats. However, in renovascular Goldblatt hypertensive rats, the dose-response curves for both NPY and NA were significantly displaced to the left, approximately threefold. Intravenous administration of BIBP 3226 (30-180 microg/kg) did not consistently lower blood pressure, per se, but did evoke competitive antagonism of the NPY pressor response in both rat populations. The magnitude of the NPY antagonism evoked by BIBP 3226 was comparable in normotensive and hypertensive rats. The absence of NA antagonism demonstrates the selectivity of the BIBP 3226 blockade.

Topics: Animals; Arginine; Blood Pressure; Disease Models, Animal; Dose-Response Relationship, Drug; Hypertension, Renovascular; Kidney; Male; Neuropeptide Y; Norepinephrine; Rats; Rats, Sprague-Dawley; Renal Artery

This study examines the influence of renal nerves on the development of renovascular hypertension in proximal aortic constricted rats. The rats were studied 1 week after unilateral or bilateral denervation of the renal artery. Denervation had no effect on the increase in mean arterial pressure induced by the constriction. The glomerular filtration rate and filtration fraction in control and in proximal aortic constricted rats were not influenced by the denervation. The Na excretion was increased in the denervated kidney both in control and in proximal aortic constricted rats. Plasma angiotensin II levels were not different from controls in innervated or unilaterally denervated proximal aortic constricted rats. In bilaterally denervated proximal aortic constricted rats the plasma angiotensin II levels were significantly higher. The renovascular hypertension and the alteration in renal function in proximal aortic constricted rats are not dependent on renal nerve activity.

Topics: Angiotensin II; Animals; Aorta, Abdominal; Blood Pressure; Calcitonin Gene-Related Peptide; Constriction, Pathologic; Denervation; Hypertension, Renovascular; Kidney; Male; Neurons, Afferent; Neuropeptide Y; Rats; Rats, Inbred Strains; Sodium

Neuropeptide Y is known to enhance blood pressure responsiveness to various constrictors, including angiotensin II, and to suppress renin secretion. This study was undertaken to assess the effect of neuropeptide Y on the development of two-kidney, one clip renal hypertension. Normotensive rats either had a silver clip placed on the left renal artery or were sham-operated upon. An osmotic minipump, which was connected via a catheter to a jugular vein, was implanted subcutaneously in all rats. These pumps delivered either neuropeptide Y (0.001 microgram/min) or saline intravenously. Eight days later, an intra-arterial catheter was inserted and the rats were studied while not anesthetized on the following day. Neuropeptide Y did not affect body weight. In clipped rats, neuropeptide Y prevented the development of hypertension and suppressed renin secretion. Neuropeptide Y significantly decreased blood pressure also in sham-operated rats, although it had no effect on plasma renin activity. These data indicate that prolonged neuropeptide Y infusion may lower blood pressure by different mechanisms, one of which is probably a suppression of renin release.

Topics: Animals; Blood Pressure; Body Weight; Hypertension, Renovascular; Infusion Pumps, Implantable; Male; Neuropeptide Y; Rats; Rats, Inbred Strains; Renin; Renin-Angiotensin System

Neuropeptide Y content of the kidneys, heart, blood vessels, adrenals and brain stem was determined in both two-kidney, one-clip and one-kidney, one-clip Goldblatt hypertension in rats and compared with levels in age- and sex-matched controls. Renal neuropeptide Y content was significantly reduced in the clipped kidney of rats in both Goldblatt two-kidney, one-clip and Goldblatt one-kidney, one-clip models of hypertension. The content of neuropeptide Y was also reduced but to a lesser extent in the contralateral, non-ischaemic kidney in the two-kidney, one-clip model. In both models of hypertension, neuropeptide Y content in the heart was significantly reduced in the left ventricle and septum but unchanged in the atria and right ventricle wall. There was no significant change in the concentration of neuropeptide Y through the vasculature (major arteries and veins), including the renal artery distal to the clip, or in adrenals and brain stem.

Topics: Adrenal Glands; Animals; Blood Pressure; Brain Stem; Female; Hypertension, Renovascular; Kidney; Myocardium; Nerve Tissue Proteins; Neuropeptide Y; Organ Size; Rats; Rats, Inbred Strains

Topics: Adult; Aged; Calcium; Epinephrine; Female; Humans; Hypertension; Hypertension, Renovascular; Male; Middle Aged; Nerve Tissue Proteins; Neuropeptide Y; Norepinephrine; Patient Compliance; Prostaglandins; Sodium; Sports; Sympathetic Nervous System