Cyclic nucleotide content of the rat anococcygeus during relaxations induced by drugs or by non-adrenergic, non-cholinergic field stimulation.
Low concentrations of sodium nitroprusside (0.2 and 1 microM) relaxed carbachol-induced tone of the rat anococcygeus but did not affect the content of either cGMP or cAMP; higher concentrations (10,100 and 1000 microM) produced greater relaxation (greater than 60%) and a rise in cGMP but not cAMP. In the presence of the cGMP-phosphodiesterase inhibitor M&B 22948 (10 microM), 1 microM sodium nitroprusside produced greater relaxation and a selective increase in cGMP. Forskolin (0.5-250 microM) caused relaxation and a selective increase in cAMP; the concentration-response relationships of the two effects were similar. Non-adrenergic, non-cholinergic (NANC) field stimulation (10 Hz; 20 s trains) reduced tone by 52% but had no effect on cyclic nucleotide content; in the presence of 10 microM M&B 22948 or 1 microM sodium nitroprusside, NANC stimulation produced a greater degree of relaxation and increased cGMP but not cAMP content. The results show that NANC stimulation acts like sodium nitroprusside, causing a selective increase in cGMP, and this supports the proposal that NANC transmission in the rat anococcygeus involves an endogenous nitrate; the possibility that multiple pools of cGMP exist in the anococcygeus is discussed.
Mirzazadeh
S
S
Smooth Muscle Pharmacology Group, King's College London, UK.
Hobbs
A J
AJ
Tucker
J F
JF
Gibson
A
A
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors; D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000037:antagonists & inhibitors; D000818:Animals; D001341:Autonomic Nervous System / Q000502:physiology*; D002217:Carbachol / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism*; D006152:Cyclic GMP / Q000378:metabolism*; D004558:Electric Stimulation; D066298:In Vitro Techniques; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism*; D009599:Nitroprusside / Q000494:pharmacology; D011688:Purinones / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
D011688:Purinones; D009599:Nitroprusside; D005576:Colforsin; D002217:Carbachol; D000242:Cyclic AMP; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D015106:3',5'-Cyclic-GMP Phosphodiesterases; C011145:zaprinast; D006152:Cyclic GMP