Radiotelemetric BP monitoring, antihypertensives and glomeruloprotection in remnant kidney model.

The mechanisms by which antihypertensives exert a glomeruloprotective effect in the remnant kidney model remain controversial. Based on periodic tail-cuff BP measurements, the variable glomeruloprotective efficacy of antihypertensive agents has been ascribed to mechanisms other than or in addition to their ability to lower BP. To more precisely define the relationship between BP control and glomeruloprotection, systolic BP was continuously monitored radiotelemetrically at 10-minute intervals for approximately 65 days in rats after approximately 5/6 renal ablation. Rats with remnant kidneys received either no therapy or one of three antihypertensive regimens in their drinking water after the first week: enalapril, a triple therapy regimen (reserpine, hydralazine, hydrochlorothiazide); or a high dose triple therapy regimen. Although all antihypertensive regimens significantly lowered BP, considerable interanimal variability was observed. Additionally, marked lability of BP was present in both untreated and treated rats. Glomerular injury in individual animals (N = 34) was very strongly correlated with their overall averaged systolic BP during the final eight weeks (r = 0.91) and with the frequency of systolic BP readings > 150 mm Hg (r = 0.89). These data do not provide evidence of a therapeutic advantage for any of the regimens independent of their antihypertensive effects but indicate that the glomeruloprotective efficacy of these antihypertensive regimens is directly proportional to their antihypertensive efficiency.