dihydropyridines and urapidil

Hypoxic pulmonary vasoconstriction (HPV) is a protective mechanism maintaining blood oxygenation by redirecting blood flow from poorly ventilated to well-ventilated areas in the lung. Such a beneficial effect is blunted by antihypertensive treatment with dihydropyridine calcium channel inhibitors. The aim of the present study was to evaluate the effect of urapidil, an antihypertensive agent acting as an α

Topics: Animals; Calcium; Calcium Channel Blockers; Calcium Channels; Calcium Signaling; Dihydropyridines; Endothelium, Vascular; Hypoxia; Lung; Piperazines; Pulmonary Artery; Swine; Vasoconstriction

Renal hemodynamic responses were studied in spontaneously hypertensive rats (SHR) and Wistar-Kyoto Rats (WKY) to two acute stresses: environmental stress (foot shock (FS) and air jet (AS)). The effects of calcium channel blocker (benidipine) and alpha 1 blocker (urapidil) on these responses were studied using an ultrasonic pulsed Doppler flowmeter. The increments in mean arterial pressure (MAP) and renal vascular resistance (RVR) were greater in SHR during both stresses. On the other hand, the decrease in the renal blood flow (RBF) with these stresses almost disappeared with renal denervation. These renal hemodynamic responses in SHR disappeared with alpha 1 blocker (urapidil), but not with calcium channel blocker (benidipine). The sympathetic nervous system became hyperactive in SHR under environmental stress, Which induced specific renal hemodynamic change. These results suggest that investigations on essential hypertension should focus on clarifying not only systemic hypertensive reaction, but also changes in renal hemodynamics. Furthermore, it is necessary for antihypertensive therapy to take these hemodynamic changes into consideration.

Topics: Acute Disease; Adrenergic alpha-Antagonists; Animals; Calcium Channel Blockers; Dihydropyridines; Female; Hypertension; Piperazines; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Renal Circulation; Stress, Physiological; Vascular Resistance