AJP - Regulatory, Integrative and Comparative Physiology, Vol 253, Issue 4 634-R639, Copyright © 1987 by American Physiological Society
Effects of parathyroid hormone on blood flow in different regional circulations
M. F. Crass 3rd, C. L. Jayaseelan and T. C. Darter
Department of Physiology, School of Medicine, Texas Tech University Health Sciences Center, Lubbock 79430.
Parathyroid hormone and, in particular, its 1-34 aminoterminal fragment,
PTH-(1-34), are potent vasodilators of the coronary circulation. In
addition the hormone exerts a powerful hypotensive effect in a variety of
animals, suggesting that the polypeptide hormone is vasoactive in
peripheral regional circulations as well. The purpose of this study was to
determine the regional circulations that were responsive and the relative
sensitivity of each to the vasoactive properties of the hormone fragment.
An anesthetized instrumented open-chest and/or open-abdomen dog model was
used. Blood flow was continuously monitored in left circumflex, left
pulmonary, right renal, celiac, and superior mesenteric arteries. Doses of
synthetic human PTH-(1-34) ranging from 0.00024 to 0.24 nmol/kg were
administered by bolus intra-arterial injections. Although PTH-(1-34)
produced a dose-related vasodilation in each of the above regional vascular
beds, marked differences in sensitivity were observed. The peptide elicited
large increases in coronary (178%) and celiac (162%) blood flow. Maximal
renal and pulmonary responses were relatively small (increases of 30 and
23%, respectively). Compared with control values, blood flow in the
superior mesenteric circulation increased only at the highest dose tested.
Thus sensitivity to the vascular effects of the hormone fragment differs
markedly between the regional vascular beds of the dog.
