Localization of sodium channel subtypes in mouse ventricular myocytes using quantitative immunocytochemistry.

摘要: Voltage-gated sodium channels are responsible for the rising phase of action potential in cardiac muscle. Previously, both TTX-sensitive neuronal (NaV1.1, NaV1.2, NaV1.3, NaV1.4 and NaV1.6) TTX-resistant channel (NaV1.5) have been detected myocytes, but relative levels protein expression isoforms were not determined. Using a quantitative approach, we analyzed z-series confocal microscopy images from individual mouse myocytes stained with either anti-NaV1.1, anti-NaV1.2, anti-NaV1.3, anti-NaV1.4, anti-NaV1.5, or anti-NaV1.6 antibodies calculated intensity staining these isoforms. Our results indicate that represented approximately 23% total channels, whereas NaV1.5 77% ventricular myocytes. These ratios consistent previous electrophysiological studies was located at cell surface, high density intercalated disc, absent transverse (t)-tubular system, suggesting support surface conduction inter-myocyte transmission. Low-level NaV1.6 suggest minor role excitation conduction. Conversely, NaV1.1 NaV1.3 localized to t-tubules likely t-tubular transmission myocyte interior. This immunocytochemical approach assessing localization provides more precise view importance possible roles may be applicable other species tissue types.