Fig. 2. Ryanodine receptor and CaN activities are required for induction of cardiac myocyte hypertrophy by isoproterenol. (A) Primary myocytes were cultured for 2 days in a minimal medium containing either no drug (a), 10 µmol/l Iso (d-f), 50 µmol/l Ry (b,e) and/or 400 nmol/l CsA (c,f). Cells were fixed and stained with antibody for the sarcomeric Z-disk protein -actinin (grayscale). Scale bar in a indicates 20 µm. (B) Mean cell surface area (± s.e.m.). ^*P<0.04 relative to the value for cells treated with Iso alone; n3 independent myocyte preparations; ANOVA, P=0.01.