Effects of neurotransmitters on calcium efflux from cultured glioma cells.
The effects of various neurotransmitters and cyclic nucleotides on 45Ca2+ efflux in cultured human glioma cells were investigated. Glutamate and glycine, but not GABA, stimulated 45Ca2+ release from the cells. Stimulation of beta-adrenergic receptors but not alpha-adrenergic receptors also increased 45Ca2+ efflux. Cholinergic receptor stimulation by carbachol had the same effect. The stimulatory effect of carbachol was abolished in the presence of either atropine or hexamethonium. C-AMP and c-GMP increased the 45Ca2+ efflux, suggesting that these agents are involved in the transmitter-stimulated release of 45Ca2+ from the cell. Kinetic analysis of the efflux revealed four calcium compartments. The carbachol-stimulated efflux represented a net release of calcium and could be ascribed to the slowest compartment. The physiological role of the transmitter-stimulated calcium release is discussed in terms of calcium-regulated stimulus-response coupling in glial-neural interaction during excitation.
D001254:Astrocytoma / Q000473:pathology*; D001285:Atropine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002132:Calcium Radioisotopes; D002217:Carbachol / Q000008:administration & dosage / Q000494:pharmacology*; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000494:pharmacology; D006152:Cyclic GMP / Q000494:pharmacology; D005971:Glutamates / Q000494:pharmacology*; D018698:Glutamic Acid; D005998:Glycine / Q000494:pharmacology*; D018738:Hexamethonium; D006584:Hexamethonium Compounds / Q000494:pharmacology; D006801:Humans; D009374:Neoplasms, Experimental; D009538:Nicotine / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology*; D010095:Oxotremorine / Q000494:pharmacology; D011458:Prostaglandins E / Q000494:pharmacology; D013997:Time Factors
D002132:Calcium Radioisotopes; D005971:Glutamates; D006584:Hexamethonium Compounds; D011458:Prostaglandins E; D018738:Hexamethonium; D018698:Glutamic Acid; D010095:Oxotremorine; D009538:Nicotine; D001285:Atropine; D002217:Carbachol; D000242:Cyclic AMP; D006152:Cyclic GMP; D002118:Calcium; D005998:Glycine; D009638:Norepinephrine