Altered renal vascular responses in the aging rat kidney.
Age-related renal functional changes may relate to alterations in the responsiveness to vasoconstrictors and vasodilators. Blood pressure and renal responses to angiotensin II (ANG II), endothelin-1 (ET), NG-nitro-L-arginine methyl ester (L-NAME), and to the ANG II receptor antagonist losartan were compared in young (3-mo-old) and older (15-mo-old) male rats. Baseline mean arterial pressure (MAP) values were slightly lower in the older rats, and glomerular filtration rate (GFR) and renal plasma flow (RPF) were higher. ANG II and ET induced comparable pressor responses in both groups but produced greater GFR and RPF reductions in the older rats. In contrast, the MAP, GFR, and RPF responses to L-NAME were exaggerated in aging rats. Losartan induced modest MAP reductions in both groups, and comparable renal vasodilatory responses. Thus the aging kidney exhibits exaggerated responses to systemic vasoconstrictor stimuli, whereas responsiveness to ANG II blockade is preserved but not enhanced. Whether or not this balance is further impaired later in the aging process remains to be determined.
Tank
J E
JE
Department of Medicine, Portland Veterans Affairs Medical Center, Oregon.
Vora
J P
JP
Houghton
D C
DC
Anderson
S
S
D000375:Aging / Q000502:physiology*; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D001713:Biphenyl Compounds / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D016232:Endothelins / Q000494:pharmacology; D005919:Glomerular Filtration Rate / Q000187:drug effects; D007093:Imidazoles / Q000494:pharmacology; D007668:Kidney / Q000187:drug effects; D019808:Losartan; D008297:Male; D019331:NG-Nitroarginine Methyl Ester; D051381:Rats; D017207:Rats, Sprague-Dawley; D012079:Renal Circulation / Q000187:drug effects; D013777:Tetrazoles / Q000494:pharmacology
D001713:Biphenyl Compounds; D016232:Endothelins; D007093:Imidazoles; D013777:Tetrazoles; D000804:Angiotensin II; D001120:Arginine; D019808:Losartan; D019331:NG-Nitroarginine Methyl Ester