RESUMO
BACKGROUND AND OBJECTIVES: The aim of this work was to study the effects of low intensity laser radiation on water transport in the toad bladder in vitro. STUDY DESIGN/MATERIALS AND METHODS: The water flow through the membrane was measured gravimetrically in bag preparations of the membrane. RESULTS: Laser radiation did not alter the water transport in the presence nor in the absence of vasopressin. In contrast, when the hemibladders were previously treated with vasopressin, the laser decreased by approximately 33.70% arginine-vasopressin (AVP)-mediated water transport. Laser radiation increased 3'5'-cyclic adenosine monophosphate (3'5'-cAMP) mediated water transport by approximately 23%. The association of laser radiation with indomethacin (IND) did not affect AVP-mediated water transport. CONCLUSIONS: This data suggests that the laser may have two effects on AVP-mediated water transport: one inhibitory effect on 3'5'-cAMP synthesis by inhibiting the adenylate cyclase complex and another stimulatory effect by inhibiting nucleotide-phosphodiesterase activity. Our results also indicate that the laser does not interfere in the prostaglandins biosynthesis induced by AVP.