Nitric oxide-mediated neurotransmission is attenuated in the anococcygeus muscle from diabetic rats.
The effect of STZ-induced diabetes of 8-weeks duration was examined on nitric oxide-mediated neurotransmission in the rat anococcygeus muscle. In the presence of noradrenergic blockade and raised tissue tone, relaxant response to nerve stimulation (0.5-5 Hz, for 10 s), sodium nitroprusside (5 and 10 nmol/l) and nitric oxide (1 and 3 mumol/l) were significantly reduced in anococcygeus muscles from diabetic rats compared to responses from control rats (p < 0.05). In contrast, relaxations to papaverine (3 and 10 mumol/l) were not reduced in tissues from diabetic rats. The nitric oxide synthesis inhibitor NOLA (100 mumol/l) abolished relaxant responses to nerve stimulation but had no effect on responses to any of the relaxant agents used. Exposure to NOLA at 10 mumol/l reduced stimulation-induced relaxations; this reduction was significantly greater in tissues from the diabetic group than from the control group (p < 0.05), probably as a consequence of the smaller relaxant responses in muscles from diabetic rats. Contractile responses to nerve stimulation (1-10 Hz, for 10 s), but not noradrenaline (0.03-30 mumol/l), were significantly greater in anococcygeus muscles from diabetic rats than from control rats (p < 0.05). NOLA (100 mumol/l) significantly enhanced stimulation-induced contractions (p < 0.05), however the enhancement was significantly less in tissues from diabetic rats (p < 0.05). The results suggest that STZ-induced diabetes impairs smooth muscle reactivity to nitric oxide in the rat anococcygeus muscle.
Way
K J
KJ
Department of Pharmacology, University of Melbourne, Victoria, Australia.
Reid
J J
JJ
D000818:Animals; D001341:Autonomic Nervous System / Q000502:physiology*; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology*; D003929:Diabetic Neuropathies / Q000503:physiopathology*; D004558:Electric Stimulation; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D009126:Muscle Relaxation / Q000502:physiology; D009130:Muscle, Smooth / Q000294:innervation*; D009569:Nitric Oxide / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D009435:Synaptic Transmission / Q000502:physiology*
D009569:Nitric Oxide