Parathyroidin effect on cerebrovascular resistance

Effects of parathyroidin in various doses on cerebrovascular resistance was studied in narcotized cats by resistography. Changes in systemic arterial pressure were recorded in parallel with this. A hypotensive dose-dependent effect of the drug was revealed, which manifested at the first minute by reduction of both arterial and perfusion pressure. The reduction of perfusion pressure reflecting a drop of cerebrovascular resistance was less pronounced than arterial pressure decrease. The said parathyroidin effect did not depend on its hypercalcemic effect which manifested much later. A suppressive action of exogenous parathyroid hormone on the transmembranous release of calcium ions in the smooth-muscle cells of the vessels is believed to underlie the detected hemodynamic shifts. These data may be useful in designing schemes of therapeutic correction of cerebral circulation disorders