Cardiovascular influences of nitrous oxide in spontaneously hypertensive rats

Cardiovascularly compromised outpatients undergoing minor elective oral surgical or dental care have not frequently received the anxiolytic and analgesic benefits of nitrous oxide ostensibly because of the reported likelihood of sympathetic nervous stimulation and possible exacerbation of hypertension or cardiac complication. Recent studies, though, have shown that the hemodynamic effects of nitrous oxide are negligible and possibly even beneficial. The present study was conducted to determine the cardiovascular effects of nitrous oxide and nitrogen (as control gas) in the spontaneously hypertensive rat (SHR) and its normotensive Wistar-Kyoto counterpart (WKY). SHRs exposed to nitrogen did not exhibit any significant change in SBP or HR, but SHRs exposed to nitrous oxide exhibited a generally concentration-related reduction in both SBP and HR. WKYs, however, displayed reductions in SBP and HR when exposed to either nitrous oxide or nitrogen. These findings indicate a difference in the hemodynamic responses of SHRs and WKYs to nitrous oxide and nitrogen. The specificity and mechanism of the nitrous oxide effects in hypertension were not determined in this study, however, these findings do indicate that nitrous oxide does not exacerbate hypertension in normal or hypertensive rats.