Calcium homeostasis during iv infusion of 1.5% glycine in anaesthetized pigs

We have examined changes in plasma concentrations of calcium in seven anaesthetized pigs during i.v. infusion of irrigating fluid containing 1.5% glycine. Volumes infused were 875 ml at 20 min (22 ml kg(-1)), 1475 ml at 40 min and 2075 ml at 60 min (75 ml kg(-1)). Plasma concentrations of sodium decreased from 134.5 (SD 3.4) to 112.8 (6.7) mmol litre(-1) at 60 min and correlated with the volume of glycine infused (r(2) = 0.73; P < 0.0001). Changes in total calcium concentrations were not statistically significant. A decrease in ionized calcium concentration was observed at 40 min (1.12 (0.05) vs 1.24 (0.04) mmol litre(-1); P < 0.05) and reached 1.11 (0.05) mmol litre(-1) at 60 min (P < 0.01). However, when corrected for pH, this decrease was not statistically significant. These results suggest that changes in plasma concentrations of sodium rather than changes in calcium homeostasis are probably more important in the development of transurethral prostatic syndrome.