The Na+, K(+)-ATPase inhibitor ouabain and the Na+ ionophore monensin have opposite effects upon carbachol-stimulated inositol phospholipid breakdown in rat cerebral cortical miniprisms.
The effects of ouabain and monensin upon basal and carbachol-stimulated inositol phospholipid breakdown in rat cerebral cortical miniprisms have been investigated. Basal inositol phospholipid breakdown was increased by both compounds at both 6 and 18 mM K+. Enhancement of the carbachol response at 6 mM, but not at 18 mM K+, was found with high concentrations of ouabain. On the other hand, monensin blocked the response to carbachol. Monensin also inhibited the specific binding of [3H]pirenzepine to cerebral cortical membranes, but this was found only at concentrations higher than required to affect the basal and carbachol-stimulated inositol phospholipid breakdown responses. Ouabain did not affect [3H] pirenzepine binding at any of the concentrations tested (6-600 muM). It is concluded that agents that increase the intracellular sodium ion concentration affect the inositol phospholipid breakdown response to carbachol, but that the modulation can be both to potentiate and to inhibit the response.
Tiger
G
G
Department of Pharmacology, University of Umeå, Sweden.
Fowler
C J
CJ
D000818:Animals; D002021:Buffers; D002217:Carbachol / Q000494:pharmacology; D002540:Cerebral Cortex / Q000378:metabolism*; D007444:Inulin / Q000494:pharmacology; D008985:Monensin / Q000494:pharmacology*; D010042:Ouabain / Q000494:pharmacology*; D010716:Phosphatidylinositols / Q000378:metabolism*; D010890:Pirenzepine / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors
D002021:Buffers; D010716:Phosphatidylinositols; D010890:Pirenzepine; D010042:Ouabain; D002217:Carbachol; D007444:Inulin; D008985:Monensin; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium