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 peri odic tail-cuff BP measurements, the variable glomeruloprotective effic acy of antihypertensive agents has been ascribed to mechanisms other t han or in addition to their ability to lower BP. To more precisely def ine the relationship between BP control and glomeruloprotection, systo lic BP was continuously monitored radiotelemetrically at 10-minute int ervals for similar to 65 days in rats after similar to 5/6 renal ablat ion. Rats with remnant kidneys received either no therapy or one of th ree antihypertensive regimens in their drinking water after the first week: enalapril, a triple therapy regimen (reserpine, hydralazine, hyd rochlorothiazide); or a high dose triple therapy regimen. Although all antihypertensive regimens significantly lowered BP, considerable inte ranimal variability was observed. Additionally, marked lability of BP was present in both untreated and treated rats. Glomerular injury in i ndividual animals (N = 34) was very strongly correlated with their ove rall 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). Thes e data do not provide evidence of a therapeutic advantage for any of t he regimens independent of their antihypertensive effects but indicate that the glomeruloprotective efficacy of these antihypertensive regim ens is directly proportional to their antihypertensive efficiency.