Effects of Elevated Pressure and Narcotic Gases on Calcium Dependent Cell Functions
Final rept. May 1988-Nov 1993
UNIVERSITY OF WESTERN ONTARIO LONDON DEPT OF PHARMACOLOGY AND TOXICOLOGY
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We have studied the effects of elevated pressures of inert and narcotic gases on calcium-dependent functions and cytosolic calcium levels in human blood platelets, marine sponge cells and cultured human SK-N-SH neuroblastoma cells using the intracellular calcium indicator fura-2 AM. We found that many of the effects of narcotic gases and of pressure He could be explained by their influence on stimulated free cytosolic Ca2 levels. This neuroblastoma cells provided much useful information. He pressure 18-36 ATA potentiated carbachol-stimulated increases in Ca2i whereas Ar and N2 did not. N2O had the opposite effect and blocked the pressure induced potentiation. Surprisingly, Xe had no effect despite being as potent an anesthetic as N2O. We conclude that some of the effects of HPNS may be due to increased Ca2 levels in neurons since- 1 this is compatible with its excitatory nature 2 the effects was opposed by narcotic gases 3 the effect was reversible when cells were compressed and decompressed before testing 4 the effect occurred at operational pressures. We further conclude that, given the different responses to N2O and Xe, they cannot be ascribed to nonspecific anesthetic effects.