The cyclic nucleotide content of the rat superior cervical ganglion
Quenzer, L.F.; Patterson, B.A.; Volle, R.L.
Journal of Pharmacology and Experimental Therapeutics 215(2): 297-303
1980
ISSN/ISBN: 0022-3565 PMID: 6255125 Document Number: 167533
Striking quantitative differences were noted in the responsiveness to K+, NaN3 and veratridine of ganglia from the rat, guinea pig and cow. Rat superior cervical ganglia were more responsive to K+- and NaN3-induced changes in cGMP than were ganglia from the guinea pig or cow, and the rat ganglia were more responsive to veratridine than were cow ganglia. The content of cGMP of rat sympathetic ganglia in vitro was raised .apprx. 50-fold by 60 mM KCl, .apprx. 8-fold by NaN3 (10-4 M) and .apprx. 30-fold by veratridine (10-4 M). The response to K+ and veratridine did not occur in denervated ganglia and depended upon Ca2+; the response to NaN3 was reduced by .apprx. 40% in denervated ganglia and did not depend upon Ca2+. The loss by denervated ganglia of the K+-induced increase in cGMP paralleled the loss of ganglionic choline acetyltransferase activity, and was complete by 24 h; the partial loss of responsiveness to NaN3 was completed by .apprx. 48 h. Cholinergic drugs (atropine, hexamethonium and physostigmine) had no effect on the cGMP response of intact ganglia to K+. Either the cGMP accumulation due to K+, veratridine or NaN3 occurred in the preganglionic nerve terminals or that K+ and veratridine, but not NaN3, released a transmitter substance (not acetylcholine) to act upon guanylate cyclase in the postganglionic neuron or glial cells. The results with denervated ganglia show that depolarization of postganglionic neurons, or glial cells by K+ and veratridine, does not lead to an increase in ganglionic cGMP. Isoproterenol (10-6 M) increased cAMP in intact ganglia by .apprx. 10-fold; 100 mM K+ increased cAMP .apprx. 2-fold. Following denervation, the increase in cAMP due to isoproterenol was reduced. The response to isoproterenol, unlike the small cAMP response to 100 mM K+, did not require Ca2+. K+ (100 mM) did not alter the maximum response to isoproterenol. Isoproterenol and K+ acted at the same site and most of the increased cAMP caused by isoproterenol occurred in postganglionic cells.