Hypertension produced by chemical renal medullectomy or partial nephrectomy in the rat: comparison of renal function and plasma volume.

Glomerular filtration rate, plasma volume and intra-arterial blood pressure were measured in conscious rats, with hypertension induced by chemical medullectomy or partial nephrectomy and compared with those in sham treated normal rats. Both medullectomy and partial nephrectomy caused a similar rise in blood pressure. Hypertension produced by partial nephrectomy was associated with plasma volume expansion but after chemical medullectomy there was a marked hypovolaemia. These results suggest that volume expansion plays no part in chemical medullectomy hypertension but are in keeping with the hypothesis that the renal medulla releases a vasodepressor substance which plays an important role in the maintenance of normal blood pressure.