Objective: ANF is a potent diuretic, natriuretic and vasorelaxant hormone. The objective of the present study was to examine the effect of opioid receptor stimulation by morphine on endogenous ANF production and diuresis after surgery.
Methods: Prospectively, nine women undergoing surgery for either uterine leiomyomas, chronic pelvic discomfort or desire for definitive contraception by laparoscopy were evaluated. Venous samples were collected at fixed times. Concentrations of ANF were measured by commercially available radioimmunassay test kits. Statistical analysis was performed by the Friedman Two-way ANOVA, Kruskal-Wallis 1-way ANOVA and Mann-Whitney U-Wilcoxon Rank Sum W Test. The level of significance was set at a probability below 0.05.
Results: There were no statistically significant changes in serum levels of ANF (p = 0.98), in diastolic blood pressure (p = 0.14) or pain score (p = 0.86) after surgery. Systolic blood pressure (p = 0.0032), pulse rate (p = 0.019) and urinary flow rate (p < 0.0001) showed significant changes during observation.
Conclusion: Our results show that i.v. administered morphine induces a potent diuretic effect via activation of opioid receptors but it can not be suggested that this effect is due to an enhanced release of ANF.