EXERCISE RENOGRAPHY IN UNTREATED SUBJECTS WITH ESSENTIAL-HYPERTENSION

Exercise induced renal dysfunction is reported to occur in treated hyp ertensive patients but not seen normotensive subjects. It is unclear i f this phenomenon is related to the disease or to treatment. Methods: Four normal volunteers and 15 hypertensive subjects (antihypertensive medications were discontinued for more than 4 wk) were studied with up right radionuclide renography at rest and during bicycle exercise, The amount of exercise was sufficient to increase the heart rate at least 20 bpm above the resting value, All subjects were healthy, without ev idence of left ventricular hypertrophy renal disease or hypertensive r etinal disease. BUN, serum creatinine concentration and urinalysis wer e normal in all subjects. Renograms were performed for 12-15 min after injection of either 1 mCi[I-123]orthoiodohippurate (OIH) or 2-7 mCi T c-99m-mercaptoacetyltriglycine (MAG3), Visual analysis and mean transi t time calculation were performed on the rest and exercise studies. Re sults: Seven of 14 hypertensive subjects and none of the normal volunt eers demonstrated abnormal prolongation in renal transit during exerci se which was not seen on the resting renogram. Four of these seven sub jects had a history of hypertension for 2 yr or less, Conclusion: Abou t 50% of individuals with mild-to-moderate hypertension and normal ren al function may have abnormal renal transit of renal excretion agents during exercise, although their baseline studios are normal, This find ing is unassociated with therapy and appears to be related directly to the pathophysiology of essential hypertension.