Differential effect of temperature on histamine- and carbachol-stimulated inositol phospholipid breakdown in slices of guinea-pig cerebral cortex.
Slices of guinea-pig cerebral cortex were incubated with [3H]-inositol at 37 degrees C before exposure to histamine or carbachol at 37 degrees C or 25 degrees C. Histamine-stimulated accumulation of [3H]-inositol 1-phosphate ([3H]-IP1) at 25 degrees C was only 5-7% of that at 37 degrees C, whereas for carbachol the response at 25 degrees C was 45-49% of that at 37 degrees C. The affinity of benzilylcholine, obtained from inhibition of carbachol-induced accumulation of [3H]-IP1 was similar at 25 degrees C and 37 degrees C, but the EC50 for carbachol was lower at 25 degrees C (20 +/- 2 microM) than at 37 degrees C (42 +/- 2 microM). The IC50 for histamine inhibition of [3H]-mepyramine binding to homogenates of guinea-pig cerebral cortex did not differ significantly at 25 degrees C and 37 degrees C. Histamine-induced accumulations of [3H]-IP2 and [3H]-IP3 at 25 degrees C, expressed as a percentage of the accumulation at 37 degrees C, were also much less than the corresponding value for carbachol. These observations imply that the locus or pathway(s) of agonist-induced formation of [3H]-IP1 are not the same for histamine and carbachol.
D000818:Animals; D002217:Carbachol / Q000494:pharmacology*; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism*; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology*; D066298:In Vitro Techniques; D007295:Inositol Phosphates / Q000378:metabolism*; D008297:Male; D019832:N-Methylscopolamine; D011738:Pyrilamine / Q000378:metabolism; D012602:Scopolamine Derivatives / Q000378:metabolism; D013403:Sugar Phosphates / Q000378:metabolism*; D013696:Temperature
D007295:Inositol Phosphates; D012602:Scopolamine Derivatives; D013403:Sugar Phosphates; D006632:Histamine; D002217:Carbachol; D011738:Pyrilamine; D019832:N-Methylscopolamine