Pregnancy-Induced Changes in Glomerular Angiotensin II Receptors in Normotensive and Spontaneously Hypertensive Rats

The binding characteristics of 125I Angiotensin II (Ang II) by glomeruli has been studied in virgin and pregnant normotensive (NTR) and spontaneously hypertensive rats (SHR). Although pregnancy induced a fall in ANG II binding by glomeruli from both strains of rats this only achieved statistical significance in NTR (p < 0.01). Pregnancy was associated with a significant increase in the binding affinity constant (Ka) for ANG II in both strains (p < 0.02). The changes induced in glomerular binding characteristics by pregnancy were unrelated to change in either plasma renin activity (PRA) or systemic blood pressure. The results of the study could explain, at least in part, the relative renal and systemic resistance to ANG II which is so characteristic of pregnancy in both humans and animals.