Tetramer positions and NND s for WT 2030_2808. (A i) A single image plane extracted from the dual-tilt tomogram of a mouse left ventricular myocyte fixed in situ. Different orthogonal planes from within the volume of the tomogram are indicated by different colors; XY in red, YZ in green, and XZ in blue. The intersection point of all three planes lies within a single ryanodine receptor and the XZ plane (blue line) was positioned to parallel, as nearly as possible, the jSR membrane, but to be within the cleft and to bisect the ryanodine receptors. Scale bar is 30 nm. (A ii) An enlarged view of the tetramer distribution (red boxes, 27 nm²) and their NNDs. (B) Data for mice that had been treated with 300 nmol/liter ISO for 2 min. M, mitochondrion; Z, Z line.