Producción CyT
Hypertension - Biphasic effect of angiotensin II on ADH-stimulated transport in the thick ascending limbs.
Congreso
Fecha:
2010Editorial y Lugar de Edición:
Lippincott Williams & WilkinsISSN:
0194-911XResumen *
Regulation of Na reabsorption at the loop of Henle controls salt homeostasis and blood pressure. Receptors for the antidiuretic hormone (ADH) and Angiotensin II (Ang II) have been described in this segment. ADH stimulates cAMP which increases transport in this segment. Ang II stimulates superoxide production, an important regulator of transport. However, the interaction of these two hormones and its effects on transport in this segment have not been evaluated. We hypothesized that Ang II increases the ADH-stimulated transport by increasing superoxide production. To test this we measured oxygen consumption in thick ascending limb suspensions from Wistar rats as a measurement of transport. We found that basal oxygen consumption was 127.817.6 nmol O2/min/mg protein. After addition of ADH (1 nM) thick ascending limbs oxygen consumption increased to 30125.8 O2/min/mg protein (p 0.01, n5). This effect was maintained throughout the experimental period. In control experiments, vehicle had no effect on oxygen consumption. Then we evaluated the effect of Ang II in ADH-stimulated transport. In the presence of Ang II (1 nM) oxygen consumption decreased to from 29529.8 to 117.911.1 nmol O2/min/mg protein and this inhibition was maintained during the first 4 minutes (p 0.006 vs ADH). However, after this transient inhibitory effect oxygen consumption was marked stimulated to 226.129.0 nmol nmol O2/min/mg protein (p 0.006 vs basal). These effects produced by Ang II were completely abolished by the AT1 receptor antagonist losartan (10 M). Since Ang II increases superoxide production in the thick ascending limb, we studied the role of superoxide in the interaction between ADH and Ang II. Información suministrada por el agente en SIGEVAPalabras Clave
thick ascending limb of HenleAngiotensin IIAntidiuretic Hormone