PRODUCTION OF POLYCLONAL ANTISERA TO PARATHYROID HYPERTENSIVE FACTOR FROM SPONTANEOUSLY HYPERTENSIVE RATS

Objective: Parathyroid hypertensive factor (PHF) is a newly described hypertensive factor which may cause elevation of blood pressure in app roximately 40% of North American essential hypertensive patients. PHF is also found in several animal models of hypertension, including spon taneously hypertensive rats (SHR), deoxycorticosterone acetate-salt hy pertensive rats and salt-sensitive Dahl rats. The objective of the pre sent study was to raise an antibody to PHF, and to use this antibody t o study the effect of PHF in SHR. Design: Plasma and parathyroid gland culture media collected from SHR were used in the present study as th e antigen in the production and analysis of a polyclonal antiserum to PHF. Methods: PHF is of low molecular weight (approximately 3000 dalto ns) and is sensitive to inactivation by trypsin. We used PHF partially purified from parathyroid gland culture media as the antigen to inocu late mice. The substance was bound to aminophenyl thioether paper disc s to make it more antigenic. The discs were then emulsified in Freund' s adjuvant (complete for first inoculation, incomplete for subsequent inoculations) for intraperitoneal implantation. Production of anti-PHF antisera was monitored by enzyme-linked immunosorbent assay.Results: Antisera produced in mice reacted with purified PHF prepared from SHR plasma as well as with PHF prepared from parathyroid gland culture med ia. PHF treated with the PHF antiserum produced no characteristic hype rtensive response in normotensive assay rats. The antisera did not cro ssreact with two forms of bovine parathyroid hormone, bPTH (1-84), bPT H (1-34) or with shorter parathyroid hormone fragments, or with any ot her vasoactive substance tested. Injection of an aliquot of the antise rum in anesthetized spontaneously hypertensive rats reduced mean arter ial pressure to a normal range of approximately 110 mmHg. Conclusions: These results indicate that (1) polyclonal antisera to PHF can be rai sed in mice and (2) PHF may contribute significantly to the elevated b lood pressure in SHR.