腎循環に関する研究 ： 血行動態からみた心房性ナトリウム利尿ペプチドの作用

Abstract

To investigate the effects of atrial natriuretic peptide (ANP) on renal hemodynamics, a comparative study was made in response to agents given before administration of ANP in 40 anesthetized dogs. After continuous administration of 5 percent glucose solution (Experiment A), captopril (Experiment B), norepinephrine (Experiment C), or angiotensinⅡ (Experiment D), ANP was given intravenously and various items were observed. Especially, outer cortical blood flow (OCBF) and inner cortical blood flow (ICBF) was measured by hydrogen clearance. The results were as follows. Experiment A : Renal blood pressure (RBP) decreased and renal blood flow (RBF) increased significantly. Therefore renal vascular resistance (RVR) decreased significantly in high dose ANP infusion. OCBF decreased and ICBF increased significantly. Experiment B: Glomerular filtration rate (GFR) and filtration fraction (FF) and RVR increased significantly in high dose ANP infusion, suggesting relative vasoconstriction of efferent arterioles. Experiment C : In low dose infusion of ANP, systemic hemodynamics showed no significant change, but RBF increased and RVR decreased significantly, which suggests the hyperreactivity of renal vessels compared with other organ vessels. GFR and FF increased, and RVR decreased, showing vasodilatation of afferent arterioles. And FE＿Nα increased significantly, which shows that sodium reabsorption was restrained at the proximal tubules. Experiment D : FE＿Nα increased significantly, which suggests that sodium reabsorption is also restrained at the distal tubules. From these results, the author concludes that ANP has different pharmacological action on afferent and efferent arterioles. And ANP gives hyperreaction on renal vessels and sodium excretion at the kidney under vasoconstrictive state.