AJP - Endocrinology and Metabolism, Vol 254, Issue 4 E435-E442, Copyright © 1988 by American Physiological Society
VIP and its homologues increase vascular conductance in certain endocrine and exocrine glands
L. J. Huffman, J. M. Connors and G. A. Hedge
Department of Physiology, West Virginia University Medical Center, Morgantown 26506.
The effects of vasoactive intestinal peptide (VIP) and related structural
homologues on tissue vascular conductances were investigated in
anesthetized male rats. VIP, peptide histidine isoleucine (PHI), secretin,
growth hormone-releasing factor (GHRF), gastric inhibitory peptide (GIP),
or saline was infused intravenously over 4 min. Tissue blood flows were
measured during this time by use of 141Ce-labeled microspheres. Regional
blood flows were normalized for any change in mean arterial blood pressure
during infusions, and results were expressed in terms of tissue vascular
conductance (C). Circulating thyrotropin (TSH), triiodothyronine (T3), and
thyroxine (T4) levels were determined before and at 20 min and 2 h after
treatment. Marked increases in thyroid, pancreatic, and salivary gland
vascular Cs occurred during peptide infusions with the order of potency
(VIP greater than PHI greater than secretin greater than GHRF greater than
GIP) correlating with the degree of structural homology to VIP. PHI and
secretin produced maximal increases in vascular Cs, which were the same as
those obtained with VIP. Circulating TSH, T3, and T4 levels were not
different from values in saline-infused rats after peptide treatments that
caused striking increases in thyroid vascular C. In the adrenal, kidney,
and testis, VIP and its homologues had little to no effect on vascular Cs.
We subsequently measured regional vascular Cs during VIP infusions in the
presence or absence of secretin.(ABSTRACT TRUNCATED AT 250 WORDS)
