Patterns of renal dopamine release to regulate diuresis and natriuresis during volume expansion: Role of renal monoamine-oxidase

Diuretic and natriuretic effects of renal dopamine (DA) are well established. However, in volume expansion the pattern of renal DA release into urine (U DA V) and the role of enzymes involved in DA synthesis/degradation have not yet been defined. The objective was to determine the pattern of U DA V during volume expansion and to characterize the involvement of monoamine-oxidase (MAO) and aromatic amino-acid decarboxylase (AADC) in this response. In this study male Wistar rats were expanded with NaCl 0.9% at a rate of 5% BWt per hour. At the beginning of expansion three groups received a single drug injection as follows: C (vehicle, Control), IMAO (MAO inhibitor Pargyline, 20 mg/kg BWt, i.v.) and BNZ (AADC inhibitor Benserazide, 25 mg/kg BWt, i.v.). Results revealed that in C rats U DA V (ng/30 min/100g BWt) increased in the first 30 min expansion from 11.5 ± 1.20 to 21.8 ± 3.10 (p La dopamina (DA) intrarrenal ejerce efectos diureticos y natriureticos. Sin embargo, en los estado de expansion de volumen aun no esta bien definido el patron de liberacion de dopamina renal hacia la orina y si cumplen un rol las enzimas involucradas en la sintesis o degradacion de la amina. El objetivo del presente trabajo fue determinar el patron de excrecion urinaria de DA (U DA V) durante la expansion de volumen, caracterizando la participacion de las enzimas monoaminooxidasa (MAO) y decarboxilasa de aminoacidos aromaticos (AADC) en esta respuesta. Para ello ratas Wistar macho fueron expandidas de volumen con NaCl 0.9% al 5% del peso corporal por hora durante dos horas y divididas en tres grupos, los que al comienzo de la expansion recibieron: C (vehiculo, Control), IMAO (Pargilina, inhibidor de MAO, 20 mg/kg PC, i.v.) y BNZ (Benserazida, inhibidor de AADC, 25 mg/kg PC, i.v.). Se observo que en C la U DA V (ng/30min/100gPC) aumento durante los primeros 30 minutos de expansion de 11.5 ± 1.20 a 21.8 ± 3.10 (p