Fig. 2.

Myogenic constriction in the afferent arteriole and interlobar artery is impaired in βENaC m/m mice. A–D: myogenic constriction in the afferent arteriole. A: image of the isolated afferent arteriole-glomerular preparation. B: inner diameter response to incubation at 60 and 120 mmHg under Ca²⁺-containing (solid lines) and Ca²⁺-free (broken lines) conditions in βENaC +/+ (■) and m/m (□) mice (n = 6). C: calculated myogenic tone is inhibited in βENaC m/m mice at 120 mmHg. D: constriction to the α-adrenergic agonist norepinephrine (NE) is similar between +/+ and m/m animals. E–G: myogenic constriction in the renal interlobar artery is impaired in βENaC mutant mice. For these experiments, m/m and m/+ mice were grouped together because responses were similar. E: calculated %myogenic tone is reduced in βENaC m/m or +/m (□, n = 5) compared with +/+ (■, n = 3) mice with stepwise increases in intraluminal pressure. F and G: vasoconstrictor responses to KCl (F) and phenylephrine (G) were identical. Data are presented as means ± SE. †Statistically different from 60 mmHg using paired, 2-tailed t-test, P < 0.05. NS, not significantly different. *Statistically different from +/+ using unpaired, 2-tailed t-test at P value indicated or 2-way repeated-measures ANOVA, with Student-Newman-Keuls post hoc test, P < 0.05.