Adrenocortical function and renal pressor mechanisms in experimental hypertension

Abstract

There is a lot of evidence — admittedly in part contradictory and confusing — that the adrenal cortex is involved in the pathogenesis of experimental as well as of various forms of clinical hypertension. We are, however, far from understanding how and where the cortical hormones interfere with the mechanisms leading eventually to the development of chronic high blood pressure. The main reasons for our lack of knowledge are the inadequacy of the methods available for assessing the functions of the adrenal cortex, the generally short observation periods, which in extreme cases may consist of only a single determination of adrenal hormone excretion, and the wide range of physiological variations in the activity of the adrenal cortex which effaces the border-line between the normal and the pathological state. Another reason why most of the efforts based on animal experiments have so far failed to elucidate the connection between the adrenal cortex and high blood pressure is the fact that the rat is much too obliging an animal for this purpose. This is exemplified not only by its ready development of hypertension in the absence of the adrenals, but also by the way in which it reacts to overdosage of adrenal hormones with chronic elevation of blood pressure. Hence we have to be most reserved in drawing general conclusions from experiments in the rat and to be cautious in assuming that mechanisms or changes demonstrable in this animal are of comparable importance or indeed involved at all in the human disease. In view of the fact that most of our experimental work to which I would like to refer was done in the rat, I have to be careful not to fall into this trap myself.