The most significant contribution to the antihypertensive drug armamentarium during recent years has been the introduction of potent drugs which affect catecholamine metabolism and release. Three such drugs—guanethidine sulfate, methyldopa, and pargyline hydrochloride—have been made available thus far. It is the purpose of this communication to (1) review the cardiorenal hemodynamic effects of these newer antihypertensive compounds, (2) compare their clinical characteristics, and (3) indicate their application in the overall drug regimen for ambulatory patients with diastolic hypertension.
Cardiorenal Hemodynamic Effects
Essential hypertension is characterized hemodynamically by increased peripheral vascular (arteriolar) resistance with normal cardiac output (Fig 1). Although renal blood flow is presumably normal at the onset of essential hypertension, progressive impairment in renal blood flow and glomerular filtration rate is an inevitable consequence of sustained diastolic blood pressure elevation. Therefore, from a cardiorenal hemodynamic standpoint, the "ideal" antihypertensive drug preferably should lower blood pressure by reducing peripheral vascular