Exercise-induced renal dysfunction studied by 99mTc-DTPA in hypertensives and normotensive controls

With the purpose of studying the effect of exercise on renal function in hypertensive patients, renal dynamic studies were performed with the aid of 99mTc-diethylenetriamine pentaacetate (DTPA). Serial renal images were taken at rest and during bicycle ergometric stress in 14 hypertensive patients (H) and 14 normotensive controls (N). Renograms were constructed, and glomerular filtration rate was determined by the method of Gates [2]. Exercise resulted in a prolongation of peak time, an increase in radioisotope retention rate at 10 minutes (10-min counts/peak counts) on renograms, and a decrease of GFR in both H and N. Plasma renin activity, aldosterone, and catecholamines were all elevated during exercise in both H and N. Our data indicate that the exercise-induced renal dysfunction demonstrated by 99mTc-DTPA renograms is not specific to H but can also be observed in N, which may have resulted from changes common to H and N, as indicated by the change of GFR and humoral factors. These findings suggest that the renal response to exercise may be a more complex pathophysiologic process than that measured by the DTPA renogram, at least in its simplified form, and should encourage further work in this area in order to elucidate the underlying process of hypertension.