Hypotensive properties of antibodies directed against an endogenous pressor peptide isolated from rat blood

Abstract

Hypertensive factor (HF), a compound isolated from the erythrocytes of rats and tentatively identified as a peptide, has been shown to influence tissue calcium metabolism and induce prolonged blood pressure elevation. In the present study, we investigated the biological properties of antibodies directed against this peptide. Partially purified antibody preparations significantly decreased HF stimulation of lanthanum-resistant calcium uptake in rat aortic tissue in vitro. Infusion of the antibody preparation into spontaneously hypertensive (SH) or normotensive Sprague–Dawley rats resulted in a rapid decline in mean blood pressure of 54 and 34 Torr (1 Torr = 133.332 Pa), respectively. In contrast, infusion of the serum immunoglobulin preparations from controls (unimmunized and ovalbumin-immunized rabbits) had no significant effect on the blood pressure of SH or normotensive rats. The systolic blood pressure of SH rats was reduced for at least 72 h following a single injection of the antibody preparations, whereas the blood pressure of normotensive rats had returned to normal levels within 24 h following antibody injection. The results indicate that the anti-HF antibody preparation antagonizes the stimulation of calcium uptake by the peptide and acutely lowers blood pressure in SH and normotensive rats.Key words: antibodies, blood pressure regulation, hypertensive factor, spontaneously hypertensive rat.