Renal hemodynamics and sodium excretion in dogs with graded valvular damage, and in congestive failure

Abstract

In an attempt to study the sequence of renal changes which occur with progressive cardiac impairment, renal plasma flow, glomerular filtration rate, sodium and water excretion were investigated in a group of dogs in the normal state, following the production of tricuspid insufficiency, and then after the superimposition of pulmonary artery stenosis, and the development of frank failure. With mild valvular damage basal CCr was unchanged, rose or fell slightly, while CPAH usually was decreased. At this stage the renal response to a rapid saline infusion was sluggish; CCr, CPAH, sodium and water excretion rose approximately 50% of normal. In frank failure basal CCr was unchanged from control levels, or only slightly reduced until late in the course of the disease. Basal CPAH was markedly reduced in all the dogs, with filtration fraction rising to 0.38 in three dogs. Saline infusion produced little or no rise of CCr and CPAH, and salt and water retention was nearly complete. It is postulated that the early decrease in renal blood flow, and the sluggish response to a saline infusion is the result of increased sympathetic nervous activity in the kidney, and is part of baroreceptor reflex tending to restore the circulation toward normal.