The thiazide-sensitive sodium-chloride-cotransporter (NCC) in the kidney distal convoluted tubule (DCT) plays an essential role in sodium and potassium homeostasis. Here, we demonstrate that NCC activity is increased by the β2-adrenoceptor agonist salbutamol, a drug prevalently used to treat asthma. Relative to β1-adrenergic receptors, the β2-adrenergic receptors were greatly enriched in mouse DCT cells. In mice, administration of salbutamol increased NCC phosphorylation (indicating increased activity) within 30 minutes but also caused hypokalemia, which also increases NCC phosphorylation. In ex vivo kidney slices and isolated tubules, salbutamol increased NCC phosphorylation in the pharmacologically relevant range of 0.01-10 μM, an effect observed after 15 minutes and maintained at 60 minutes. Inhibition of the inwardly rectifying potassium channel (Kir) 4.1 or the downstream with-no-lysine kinases (WNKs) and STE20/SPS1-related proline alanine-rich kinase (SPAK) pathway greatly attenuated, but did not prevent, salbutamol-induced NCC phosphorylation. Salbutamol increased cAMP in tubules, kidney slices and mpkDCT cells (model of DCT). Phosphoproteomics indicated that protein phosphatase 1 (PP1) was a key upstream regulator of salbutamol effects. A role for PP1 and the PP1 inhibitor 1 (I1) was confirmed in tubules using inhibitors of PP1 or kidney slices from I1 knockout mice. On normal and high salt diets, salbutamol infusion increased systolic blood pressure, but this increase was normalized by thiazide suggesting a role for NCC. Thus, β2-adrenergic receptor signaling modulates NCC activity via I1/PP1 and WNK-dependent pathways, and chronic salbutamol administration may be a risk factor for hypertension.
Keywords: NaCl cotransporter; SPAK; WNK kinases; adrenergic; adrenoceptor; blood pressure; salt-sensitive hypertension.
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