Norepinephrine increases Na+-K+-ATPase and solute transport in rabbit proximal tubules.
We studied the effects of norepinephrine on solute transport and oxidative metabolism in proximal tubules. Norepinephrine (10(-6) M) in the bath stimulated fluid absorption (Jv) by proximal convoluted tubules from 0.76 +/- 0.10 to 1.01 +/- 0.11 nl X mm-1 X min-1 (P less than 0.001). Bicarbonate, chloride, and phosphate transport also increased in proportion to the increases in Jv. Norepinephrine increased ouabain-sensitive oxygen consumption (QO2) in suspensions of cortical tubules by 1.3 nmol X mg protein-1 X min-1 and had no effect on ouabain-insensitive QO2 or mitochondrial respiration. Na+-K+-ATPase activity in basolateral membranes prepared from cortical homogenates incubated with norepinephrine increased from 277.1 +/- 34.9 to 411.1 +/- 38.6 nmol Pi X mg protein-1 X min-1 (P less than 0.005). Norepinephrine also increased Na+-K+-ATPase activity of cortical homogenates by 72% but had no effect on Na+-K+-ATPase if added directly to purified basolateral membranes. These studies show that norepinephrine stimulates solute transport in the proximal tubule by increasing Na+-K+-ATPase activity indirectly through some component or components of the adrenergic receptor system.
D000818:Animals; D001692:Biological Transport; D005260:Female; D066298:In Vitro Techniques; D007687:Kidney Tubules, Proximal / Q000201:enzymology / Q000378:metabolism*; D009638:Norepinephrine / Q000494:pharmacology*; D010084:Oxidation-Reduction; D011817:Rabbits; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D000254:Sodium-Potassium-Exchanging ATPase; D009638:Norepinephrine