Evidence for tetrodotoxin-sensitive sodium currents in primary cultured myocytes from human, pig and rabbit arteries

Primary cultured human coronary myocytes express a tetrodotoxin-sensitive sodium current (INa). Here, we have investigated whether INa is expressed in vascular smooth muscles cells (VSMCs) isolated from other large arteries, and other mammals. VSMCs were enzymatically dissociated, kept in primary culture, and macroscopic INa was recorded using the whole-cell patch-clamp technique. We found that INa is expressed in VSMCs grown from human aortic (90%; n=50) and pulmonary (44%; n=19) arteries, and in the human aortic myocyte cell line HAVSMC (94%; n=27). INa was also detected in pig coronary (60%; n=33), and rabbit aortic (47%; n=15), but not in rat aortic VSMCs (n=20). These different INa had similar voltage thresholds for activation (≅–50 mV), and were highly sensitive to extracellularly applied tetrodotoxin. We conclude that INa is expressed in VSMCs grown from various types of large arteries in humans, pig and rabbit.