Calcium antagonists preferentially dilate preglomerular vessels of hydronephrotic kidney.
The hydronephrotic kidney of Inactin-anesthetized female Wistar rats was exteriorized in a controlled bath to directly observe preglomerular and postglomerular vessels via television microscopy. Nitrendipine, added to the bath in a concentration that did not alter blood pressure, induced a concentration-dependent dilation of preglomerular vessels. The arcuate artery maximally dilated by 29 +/- 4%, the interlobular artery by 24 +/- 5%, the afferent arteriole near the interlobular artery by 60 +/- 9%, and near the glomerulus by 28 +/- 13%. In contrast the efferent arteriole near the glomerulus dilated by only 11 +/- 6% and near the welling point by 7 +/- 9%. Similarly, diltiazem significantly dilated preglomerular vessels but not efferent arterioles. Acetylcholine significantly dilated all preglomerular vessels and dilated the afferent arterioles near the glomerulus (by 51 +/- 8%) to a greater extent than the calcium blockers. Acetylcholine also significantly dilated the efferent arterioles (near the glomerulus by 26 +/- 5% and near the welling point by 12 +/- 3%). These data suggest that the tone of the preglomerular vessels of the hydronephrotic kidney is more dependent on the entry of extracellular calcium through calcium antagonist-sensitive channels (i.e., potential dependent) than is the tone of the afferent arterioles near the glomerulus and the efferent arterioles.
Department of Physiology, University of Louisville, Kentucky 40292.
J T
JT
Fleming
N
N
Parekh
M
M
Steinhausen
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D004110:Diltiazem / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D006869:Hydronephrosis / Q000503:physiopathology*; D007678:Kidney Glomerulus / Q000098:blood supply*; D009568:Nitrendipine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors; D014664:Vasodilation / Q000187:drug effects*
D002121:Calcium Channel Blockers; D009568:Nitrendipine; D004110:Diltiazem; D000109:Acetylcholine