AJP - Endocrinology and Metabolism, Vol 263, Issue 4 E740-E747, Copyright © 1992 by American Physiological Society
Effects of peptide YY on the human cardiovascular system: reversal of responses to vasoactive intestinal peptide
R. J. Playford, M. A. Benito-Orfila, P. Nihoyannopoulos, K. A. Nandha, J. Cockcroft, S. Todd, M. A. Ghatei, J. Domin, S. R. Bloom and J. Calam
Department of Medicine, Royal Postgraduate Medical School, London, United Kingdom.
Peptide YY (PYY) reverses the increased intestinal secretion stimulated by
vasoactive intestinal peptide (VIP) in humans. VIP also dilates blood
vessels, so we investigated the effect of PYY on the cardiovascular system.
Six volunteers received PYY, 0.4 and 1.2 pmol.kg-1 x min-1 i.v. for 2 h,
reproducing plasma levels seen postprandially and during a diarrheal
illness, respectively. Cardiac function was assessed by echocardiography.
PYY infused at 0.4 pmol.kg-1 x min-1 had no effect on cardiovascular
parameters. PYY infused at 1.2 pmol.kg-1 x min-1 caused a fall in both
stroke volume from 128 +/- 8 to 110 +/- 8 ml/beat (mean +/- 95 confidence
interval, P < 0.01) and cardiac output from 7.2 +/- 0.4 to 6.1 +/- 0.4
l/min (P < 0.01). Effects of infusion of PYY into the brachial artery at
doses of 0-16 pmol/min were assessed using venous occlusion plethysmography
in six subjects. PYY infusion caused a dose-dependent fall in forearm blood
flow. Six subjects received VIP, 5 pmol.kg-1 x min-1 i.v., causing a rise
in heart rate from 55 +/- 3 to 70 +/- 3 beats/min and increased cardiac
output from 7.3 +/- 1.1 to 13.1 +/- 1.1 l/min. The addition of PYY, 0.4
pmol.kg-1 x min-1 i.v., did not affect the heart rate significantly but
decreased the cardiac output to 10.4 +/- 1.1 l/min (P < 0.01). Infusions
of PYY into the brachial artery at 5 pmol/min decreased local vasodilation
induced by VIP infused at 2 pmol/min at the same site by 40% (P < 0.01),
even though this dose of PYY had no significant effect on local blood flow
when given alone.(ABSTRACT TRUNCATED AT 250 WORDS)
