Effect of nasogastric administration of sodium bicarbonate on carbon 13 isotopic enrichment of carbon dioxide in serum of horses

Abstract

Objective - To determine the effect of administration of commercially available sodium bicarbonate (NaHCO3) on carbon 13 (13C) isotopic enrichment of carbon dioxide (CO2) in serum of horses. Animals - 7 healthy Thoroughbreds. Procedures - Sodium bicarbonate (450 g) was administered via nasogastric intubation to horses. Horses had been fed a diet obtained from the same source and had access to water from the same source for 3 months before the study. Blood samples were collected immediately before and at 2, 4, 6, and 24 hours after administration of NaHCO3. The concentration of total CO2 in serum was measured by use of a commercial analyzer. The 13C enrichment of bicarbonate in serum was estimated by measurement of 13C enrichment of CO2 released by acidification of the serum. The 13C enrichment of commercially available NaHCO3 was also determined and compared with that of CO2 in serum of horses before administration of NaHCO3. Results - Commercially available NaHCO3 had a 13C enrichment significantly different from that of carbon dioxide in serum of horses before treatment. Administration of NaHCO3 increased the concentration of total CO2 from pretreatment values. The 13C enrichment of CO2 in serum was only transiently and minimally affected after administration of NaHCO3. Conclusions and Clinical Relevance - Administration of NaHCO3 was not detected by measuring 13C enrichment of CO2 in serum of horses.