title: Correlations between Na+-K+ ATPase activity and acetylcholine release in rat cortical synaptosomes.
abstract: [3H]Acetylcholine efflux and Na+-K+ ATPase ion pump activity were measured concomitantly in rat cortical synaptosomes. Ouabain (500 microM), strophanthidin (500 microM), and parachloromercuribenzene sulfonate (500 microM) each inhibited ouabain-sensitive 86Rb uptake and elevated [3H]acetylcholine release independently of the external calcium concentration. Veratridine (10 microM), electrical field stimulation (60 V, 60 Hz, 5-ms pulse duration), or the calcium ionophore A23187 (10 micrograms/ml) also inhibited ouabain-sensitive 86Rb uptake and released [3H]acetylcholine, but via a calcium-dependent process. Veratridine-induced [3H]acetylcholine release and ion pump inhibition were correlated over a wide range of drug concentrations and both effects were blocked by pre-treatment with tetrodotoxin (1 microM). The rate of [3H]acetylcholine efflux from superfused synaptosomes was increased within 15 s of exposure to ouabain, strophanthidin, veratridine, A23187, or field stimulation, while ouabain-sensitive 86Rb uptake was significantly decreased within a similar interval. These results suggest that [3H]acetylcholine release is due at least in part to inhibition of Na+-K+ ATPase.
mesh_terms: D002731:4-Chloromercuribenzenesulfonate / Q000494:pharmacology; D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D000001:Calcimycin / Q000494:pharmacology; D002540:Cerebral Cortex / Q000378:metabolism*; D004558:Electric Stimulation; D008297:Male; D010042:Ouabain / Q000494:pharmacology; D051381:Rats; D012413:Rubidium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013327:Strophanthidin / Q000494:pharmacology; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*; D014701:Veratridine / Q000494:pharmacology
chemical_list: D000001:Calcimycin; D010042:Ouabain; D002731:4-Chloromercuribenzenesulfonate; D013327:Strophanthidin; D014701:Veratridine; D000254:Sodium-Potassium-Exchanging ATPase; D012413:Rubidium; D000109:Acetylcholine