Comparison of the effects of antihypertensive drugs on pre- and postglomerular vessels of the hydronephrotic kidney.
The in vivo renal microvascular effects of three antihypertensive drugs: nitrendipine, a calcium entry blocker, and two direct-acting vasodilator agents, hydralazine and minoxidil, were compared. The dilator responses of pre- and postglomerular vessels were directly observed after the topical or intravenous administration of each drug using the hydronephrotic kidney preparation and television microscopy. When applied directly to the kidney to avoid changes in systemic blood pressure, all three drugs preferentially dilated the preglomerular vessels. The largest increases in preglomerular vessel diameters were observed with nitrendipine followed by hydralazine and minoxidil, in the order listed. These drugs produced little change in efferent arteriole diameters though acetylcholine evoked significant dilator responses of the same vessels. When infused intravenously to lower blood pressure, the predominant effect of the drugs was on the afferent arteriole. No significant changes in the efferent arteriole diameter were observed with any drug. These data demonstrate that these vasodilators, which act primarily at preglomerular sites, probably increase glomerular capillary pressure, but to differing degrees.
Fleming
J T
JT
Department of Physiology and Biophysics, University of Louisville, Kentucky 40292.
Garthoff
B
B
Mayer
D
D
Rosen
B
B
Steinhausen
M
M
D000287:Administration, Topical; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001160:Arterioles / Q000187:drug effects; D005260:Female; D006830:Hydralazine / Q000494:pharmacology; D006869:Hydronephrosis / Q000503:physiopathology*; D007275:Injections, Intravenous; D007678:Kidney Glomerulus / Q000098:blood supply* / Q000187:drug effects; D008833:Microcirculation / Q000187:drug effects; D008914:Minoxidil / Q000494:pharmacology; D009568:Nitrendipine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D014664:Vasodilation
D000959:Antihypertensive Agents; D006830:Hydralazine; D008914:Minoxidil; D009568:Nitrendipine