Modification of epinephrine-induced inhibition of transmission by tropolone and desipramine (desmethylimipramine) in the perfused superior cervical ganglion
✍ Scribed by Frederick J. Goldstein; Frederick B. Giller; G. Victor Rossi
- Publisher
- John Wiley and Sons
- Year
- 1969
- Tongue
- English
- Weight
- 361 KB
- Volume
- 58
- Category
- Article
- ISSN
- 0022-3549
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✦ Synopsis
0 Tropolone, an inhibitor of catechol-0-methyltransferase (COMT), and desipramine (desmethylimipramine, DMI), which impairs catecholamine uptake at presynaptic adrenergic membranes, were introduced into the superior cervical ganglion of the cat. Throughout a wide dosage range (3.12-800 mcg.) tropolone exerted a negligible effect on epinephrine-induced inhibition of ganglionic transmission. COMT does not appear, therefore, to participate to a significant extent in peripheral ganglionic inactivation of circulating epinephrine. DMI in doses (125 and 250 mcg.) which alone had no effect on postganglionic potentials facilitated the depression of ganglionic transmission by epinephrine. Potentiation of epinephrine activity by DMI is attributed to a decrease in catecholamine uptake capacity at ganglionic sites. Catecholamine uptake thus appears to be a factor in terminating the activity of circulating epinephrine a t sympathetic ganglia. Evidence for the existence in the ganglion of an uptake mechanism lends support to the proposal that catecholamines may function in the regulation of peripheral sympathetic ganglionic transmission.