FIG. 3.

Toxin B inhibits phosphorylation of JNKs but not of p38-MAPKs induced by ET-1 or hyperosmotic shock. Myocytes were unstimulated (controls) or were exposed to 0.5 M sorbitol (Sorb) (A and C) or 10 nM ET-1 (B and D) with or without pretreatment with toxin B (ToxB) (10 ng/ml, 1 h) for 0 or 30 min in the case of JNKs or for 0, 3, or 10 min in the case of p38-MAPKs. (A and B) Extracts were immunoblotted for phosphorylated (activated) JNKs (Phospho-JNKs) or total JNKs. The upper arrow on each blot indicates the 54-kDa JNKs, whereas the lower arrow indicates the 46-kDa JNKs. (C and D) Extracts were immunoblotted for phosphorylated (activated) p38-MAPKs (Phospho p38-MAPK) or total p38-MAPKs. Blots were analyzed by scanning densitometry (A to D, lower panels) Results are means ± SEM for three or four separate myocyte preparations. ∗, P < 0.001 relative to hyperosmotic shock in the absence of toxin B (unpaired two-tailed t test).