Influence of Calcium Antagonists on Kidney Function of Hypertensive Rats

Abstract

Calcium antagonists (CA) are important drugs used mainly in the treatment of various types of hypertension [15, 20, 22]. Their effect on the kidney in health and disease has been excellently reviewed [15, 18, 19]; therefore, I thought it much more reasonable, instead of trying to concoct another review article, to report on experiments carried out in our laboratory adressing this topic. Vasodi– latation seems to be the main effect of CA, and this also encompasses the kidney [3, 24, 26], especially its main resistance vessels, the afferent and efferent arterioles. In a hydronephrotic kidney, vasodilatation is more pronounced on the afferent than on the efferent arteriole [4, 17]; this could be dangerous since an increase in glomerular capillary pressure followed by hyperfiltration may occur, both events supposed to be deleterious [1, 11]. However, the hydronephrotic kidney is a rather sophisticated preparation far from the physiological State. Therefore, we decided to study this question in anesthetized dogs in which the CA were infused directly into the left renal artery (LRA) at a dose not influencing systemic blood pressure [8]. Nevertheless, the acute effects of CA are clinically not very important, since hypertensive patients take the drugs regularly and over long periods of time. The effect of systemic long–term administration of CA was studied in rats.