Effect of barbituric acid on the high pressure nervous syndrome in the rat.

Male Sprague-Dawley rats were compressed in helium-oxygen mixture at a rate of 3 bar/min. Compression ended once the first convulsion was seen. Saline or barbituric acid at 1 or 2% were infused continuously during compression at a rate of 9.49 ml/h (tail vein). With barbituric acid at 1%, coarse tremor and convulsions appeared at higher pressures than in saline controls. No significant change was observed with 2% barbituric acid compared to saline controls. Barbituric acid which is nonanesthetic had some anti-high pressure nervous syndrome (HPNS) activity which is dose dependent. These results suggest that anti-HPNS activity of these different compounds involves at least one site which is different from that responsible for anesthetic activity.