Renal hemodynamic responses to stress in normotensive and hypertensive subjects

Bello, C.T.; Sevy, R.W.; Ohler, E.A.; Papacostas, C.A.; Bucher, R.M.

Circulation 22(4 Part 1): 573-582


ISSN/ISBN: 0009-7322
DOI: 10.1161/01.cir.22.4.573
Accession: 025378437

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Renal responses to stress were studied in 28 normotensive and 51 hypertensive patients. Renal clearances of inulin (Cin) and PAH (C), filtration fraction, arterial blood pressure, and renal vascular resistance were determined in each patient immediately before, during, and immediately after exercise (sit-ups), or the cold pressor test. The pattern of response to stress was similar in normotensive and untreated hypertensive patients: reduction in Cin and Cpah, and in-creases in filtration fraction, blood pressure and renal vascular resistance. These responses were more marked with exercise than with the cold pressor test. These responses to stress were also quantitatively similar in normotonsive and untreated hypertensive subjects, except for renal vascular resistance which was increased more in the hypertensive groups. However, hyperreactivity in terms of vascular resistance is not necessarily indicative of vascular smooth muscle hyperreactivity. The renal responses to exercise or the cold pressor test were reduced or abolished in hypertensive subjects by sympathectomy, and were diminished, in the majority of patients, by therapy with reserpine. Neither sympathectomy nor reserpine affected control (pre-stress) values for renal clearances or renal vascular resistance, however. The majority of patients with malignant hypertension, though showing severely reduced values for Cin and Cpah, and marked elevations in renal vascular resistance initially, showed minimal renal responses to exercise or the cold pressor test.