Effect of chronic hypoxia on ion channel development in cultured cardiac cells
Guo, W.; Kamiya, K.; Toyama, J.
Environmental Medicine Annual Report of the Research Institute of Environmental Medicine Nagoya University 39(1): 57-60
1995
ISSN/ISBN: 0287-0517 PMID: 11540542 Document Number: 447360
In order to investigate mechanisms underlying the postnatal development of the transient outward current (I-to) in the rat heart, we established a primary culture of neonatal rat ventricular myocytes and studied the modulated expressions of I-to under normoxic (21% O-2) and hypoxic (7.5% O-2) growth conditions. During development from day 5 to day 15 in the normoxic cultures, I-to density doubled without any changes to the kinetics of current inactivation. Chronic hypoxia from day 6 to day 15 prevented this increase in I-to density. The reduced expression of I-to under hypoxic conditions was due to the loss of the fast inactivating component of I-to (I-to,f). These observations suggest that ion channels in neonatal rat cardiomyocytes in primary culture are not constitutively expressed but can be regulated by extrinsic factors. The postnatal increase in I-to density among newborn rats is closely associated with an alteration in oxygen tension.