ESTIMATIONS OF AFFERENT ARTERIOLE AND GLOMERULAR CAPILLARY PRESSURES IN THE FROG KIDNEY

Abstract

A method was developed for altering and measuring the pressure within a capsule of Bowman in the frog''s kidney which permits the estimation of blood pressure in glomerular capillaries and in the afferent artery by an application of the Riva-Rocci principle. Over 190 such estimations have been made during simultaneous record of aortic pressure. Systolic pressures in the aorta ranged from 21 to 61 cm. H2O; in the afferent artery, 15 to 56 cm. H2O; glomerular capillary pressure varied between 4 and 52 cm. H2O. Systolic pressure in the afferent artery averaged 85% of simultaneous aortic pressure; pressure in the glomerular capillaries, 54%. In general there is a high direct correlation between systolic aortic and systolic afferent artery pressures, between systolic capillary, and between systolic afferent artery and capillary pressures. In a few experiments in which the action of adrenalin and caffein were tested, the results agreed with the view that a substance by action on either afferent or efferent vessel may influence glomerular capillary pressure to a degree quite out of proportion to its effect on aortic pressure. Under these circumstances the correlation between aortic and capillary pressure is in abeyance.