[Changes in erythrocyte P50 and its effect on O2 transport in intravenous tocolysis with fenoterol (Partusisten)].

Fenoterol (Partusisten), which has a considerable influence on glucose metabolism in addition to its well-known cardiac side-effects, does not appear to have any direct influence on the P50 of the maternal erythrocytes in in-vitro experiments. In incubation experiments with fresh erythrocytes, fluctuations in the P50 with an amplitude of 2-5 mmHg were measured at +37 degrees C; these fluctuations depend on the storage age of the erythrocytes and the glucose content of the incubation medium. Fenoterol has no effect on the amplitude, nor on the frequency of this P50 fluctuation. The glycolytic activity of the erythrocytes, relative to the 2,3-DPG and ATP content, also remains uninfluenced under Fenoterol. The addition of progesterone or cortisone to the incubation medium has no influence on the P50 of the maternal erythrocytes. In-vivo studies of the blood of pregnant women indicate changes of the P50 with maximal "shift to the left" after 6 hours and compensatory "shift to the right" after 20 hours under tokolysis. No fluctuations of the pH value were observed in our patients. The intraerythrocytic 2,3-DPG concentration changes simultaneously with the P50. Venous pO2 increases by approx. 12 mmHg in the first 3 hours following the start of tokolysis. However, the changes in the venous pO2 are not simultaneous with the changes in the P50. It can be stated that the progesterone level has no influence on the release of O2 from the maternal blood.(ABSTRACT TRUNCATED AT 250 WORDS)