The intrarenal blood flow distribution and role of nitric oxide in diabetic rats.
A few attempts have so far been made to determine the regional renal blood flow distribution in experimental diabetic rats. In the present experiment, 3 weeks after successful streptozotocin injection in diabetic rats (n = 8), the blood flows in the renal superficial and deep cortexes and outer medulla with implanted fibers were measured by laser-Doppler techniques. Renal blood flow was measured by an ultrasonic flow probe placed around the renal artery. Studies were performed at the baseline condition, during the administration of nonselective nitric oxide synthesis inhibitor, nitro- l -arginine methyl-ester ( l -NAME), and during the postinfusion period. The results showed that superficial cortical blood flow and deep cortical blood flow were significantly greater ( P < .05) in diabetic rats compared with control rats (n = 8) (superficial cortical blood flow, 2.18 +/- 0.22 vs 1.55 +/- 0.21 V; deep cortical blood flow, 1.32 +/- 0.13 vs 0.99 +/- 0.14 V) with the significant increase in renal blood flow (18.1 +/- 3.3 vs 14.5 +/- 2.7 mL/min). Furthermore, it was shown that in diabetic rats the intravenous infusion of a low dose of l -NAME, which did not alter medullary blood flow, decreased cortical blood flow (CBF) ( P < .05), whereas in control rats l -NAME did not affect CBF but a high dose of l -NAME decreased medullary blood flow ( P < .05). We conclude that in early diabetic nephropathy the blood flow is increased in both the superficial and deep cortexes, and nitric oxide plays an important role in regulating the CBF during the development of diabetic nephropathy.
Nakanishi
Kazushige
K
Second Department of Internal Medicine, Toho University School of Medicine, 143-854, Tokyo, Japan. kazunaka@med.toho-u.ac.jp
Onuma
Shizuka
S
Higa
Mariko
M
Nagai
Yohko
Y
Inokuchi
Toshiki
T
D000818:Animals; D001794:Blood Pressure; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology*; D003928:Diabetic Nephropathies / Q000503:physiopathology; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012079:Renal Circulation; D013311:Streptozocin
D009569:Nitric Oxide; D013311:Streptozocin; D019331:NG-Nitroarginine Methyl Ester