Table 2 shows the estimated means of NERL ad- justed values for plasma tCO2 by hour for 0, 250, and 500 mg furosemide doses, the pooled standard error (SE) and lower (mean – 1.96 ϫ SE) and upper (mean + 1.96 ϫ SE) confidence limits for the plasma tCO2 val- ues.The elevation of plasma tCO2 after the administra- tion of either 250 or 500 mg furosemide is apparent. A reduction in plasma tCO2 appears at all dosage levels, including the control, by hours 5 or 6 after treatment, which may suggest some cyclic variation in plasma tCO2 throughout the day in addition to the expected attenu- ation of the furosemide effect over several hours.