Lack of effect of acute prolactin suppression on renal water sodium and potassium excretion during sleep.

The possible role of endogenous prolactin (hPRL) in the regulation of renal water, Na and K excretion during sleep was tested in a group of 10 healthy female volunteers. Plasma hPRL and total urinary Na and K excretion were measured at 2- and 4-hourly intervals, respectively, in the control period and after prolactin inhibition with bromocriptin. Despite adequate prolactin suppression, no significant changes were observed in the nyctohemeral excretion rhythms of water, Na and K, suggesting that endogenous prolactin is not instrumental in the control of these parameters.