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Alpha-adrenoceptor and dopamine receptor antagonists do not block the slow inhibitory postsynaptic potential in sympathetic ganglia
| Content Provider | Semantic Scholar |
|---|---|
| Author | Cole, Alison E. Shinnick-Gallagher, Patricia |
| Copyright Year | 1980 |
| Abstract | In sympathetic ganglia, stimulation of preganglionic fibers generates a nicotinic fast excitatory postsynaptic potential (F-EPSP) followed by muscarinic slow potentials. Eccles and Libet 7 proposed that the slow inhibitory postsynaptic potential (S-IPSP)* was mediated by a disynaptic pathway. According to the hypothesis, an interneuron, in response to muscarinic excitation, releases a catecholamine which initiates the S-IPSP. Libet 17 proposed dopamine as the catecholamine neurotransmitter involved in this response. If catecholamines are responsible for the S-IPSP, application of exogenous catecholamines should elicit a response identical to the S-IPSP. Catecholamines do hyperpolarize sympathetic ganglia3,5,6, 21. However, to fulfill the criteria that establish agents as neurotransmitters of the physiological response, investigators must prove that the same antagonists block both the catecholamine-induced hyperpolarization and the S-IPSP. In this paper, we report that the S-IPSP in the rabbit superior cervical ganglion (RSCG) is not specifically blocked by catecholamine antagonists. Superior cervical ganglia were excised from adult male New Zealand white rabbits. Responses were recorded from ganglia by a modified sucrose gap techniquelL A physiological solution of the following composition was used to superfuse the preparation (mM): NaC1, 117; KC1, 4.7; CaCI2, 2.5; MgCI2, 1.2; NaHCO3, 25; NaH2PO4, 1.2; glucose, 11.5. We routinely added hexamethonium (5 × 10 -4 M) to the superfusate to block the fast excitatory nicotinic response. Drugs were added to the physiological solution and administered by superfusion. Train stimulation of the preganglionic nerve at 40 Hz for 250 msec elicited a maximal S-IPSP response. We initially studied the effects of dopamine antagonists on the S-]PSP response in RSCG. Ganglia were superfused with increasing concentrations (10-8-10 -3 M) of sulpirixle (n = 7) and haloperidol (n = 3). At concentrations of 10-8-10 -6 M no de- |
| Starting Page | 226 |
| Ending Page | 230 |
| Page Count | 5 |
| File Format | PDF HTM / HTML |
| DOI | 10.1016/0006-8993(80)90510-7 |
| PubMed reference number | 6244069 |
| Journal | Medline |
| Volume Number | 187 |
| Alternate Webpage(s) | https://api.elsevier.com/content/article/pii/0006899380905107 |
| Alternate Webpage(s) | https://www.sciencedirect.com/science/article/pii/0006899380905107?dgcid=api_sd_search-api-endpoint |
| Alternate Webpage(s) | https://doi.org/10.1016/0006-8993%2880%2990510-7 |
| Journal | Brain Research |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
