Ca2+ current‐gated focal and local ca2+ release in rat atrial myocytes: evidence from rapid 2‐d confocal imaging

• DOI: 10.1113/jphysiol.2002.024190
• Publication Date: 2002-08-30T21:23:00Z
• Authors: Sun‐Hee Woo; Lars Cleemann; Martin Morad
• Keywords: EGTA

In atrial myocytes immunocytochemistry has shown two groups of ryanodine receptors (RyRs): those at the periphery colocalized with dihydropyridine (DHPRs) and cell interior not associated DHPRs. The extent to which sets RyRs are controlled by Ca2+ current (I(Ca)) or diffusion remains be determined. Here, using rapid (240 Hz) two-dimensional confocal imaging in rat myocytes, we examine directly role I(Ca) on patterns local focal releases. evoked peripheral release within 1-4 ms, causing a monophasic rise Ca2+, then propagated into along sarcomeric lines (approximately 2 microm) velocity approximately 230 microm s(-1), even though found no evidence for organized t-tubules di-8-ANEPPS staining. I(Ca)-triggered centre, other hand, had both (12 ms) slower delayed components (12-50 ms). voltage dependence central was bell shaped, magnitude each component linearly related I(Ca). Premature termination (2-10 equally effective abbreviating slow release. High concentration buffers (2-5 mM EGTA plus 1 fluo-3) completely abolished I(Ca)-gated propagation wave release, but little effect efficacy trigger myocyte 5 times higher than consistent smaller measured quantification as function suggests cooperative gating mechanism(s) These findings indicate that from sites contribute SR. How fact I(Ca)-dependent fast is activated