[The effect of metoprolol on fenoterol-induced kidney function disorders]

The effect on renal function of a combination of a beta 2 receptors stimulating tokolytic agent (Fenoterol) with a so-called cardioselective beta 1 blocker (Metoprolol) which is able to antagonise the cardiac side effects of beta 2 stimulation, was examined in femaLe rabbits in a 24-hour test. Infusing 31.5 ml/h isotonic solution, 20 micrograms/kg/min Fenoterol and 3.125 micrograms/kg/min Metoprolol, excretion, creatinine clearance, electrolyte elimination, the serum electrolyte levels, Hb, HK and the weight were determined. The combination of Fenoterol and Metoprolol antagonised almost completely the massive water retention occurring under Fenoterol alone. At the latest after 12 hours, normal values were obtained in respect of the creatinine clearance reduced under Fenoterol, the urine excretion rate and, consequently, the Hb concentration and haematocrit reading. The reduction of sodium elimination caused by Fenoterol was completely reversed under the combination, whereas the reduced excretion of potassium was not influenced. Water retention in tocolysis with beta 2 stimulants is one of the most important causes for the information of a pulmonary oedema. The danger of the occurrence of such pulmonary oedemas, especially in risk pregnancies (gestosis), is drastically reduced by antagonising water retention, and hence the combination of Fenoterol and Metoprolol seems to be very favourable from both the cardiac and renal viewpoints. In a group of 17 pregnant women, the drastic improvement of urine excretion under the combination could be confirmed.