Ageing, gender and cardiac sarcolemmal K(ATP) channels

作者：Jovanovic Aleksandar^*

来源：Journal of Pharmacy and Pharmacology, 2006, 58(12): 1585-1589.

DOI：10.1211/jpp.58.12.0004

Sarcolemmal ATP-sensitive K(+) (K(ATP)) channels are abundant in cardiac myocytes where they couple the cellular metabolic state with membrane excitability. Structurally, these channels are composed of Kir6.2, a pore-forming subunit, SUR2A, a regulatory subunit, and at least four accessory proteins. The activation of KATP channels occurs during ischaemia to promote cardiac viability under this adverse condition. Age-dependent changes in the myocardial susceptibility to ischaemia have been reported in experimental animals as well as in humans. Recent research has demonstrated that ageing is associated with a decrease in the number of cardiac sarcolemmal KATP channels in hearts from females, but not males. This alteration is likely to be due to an age-dependent decrease in the concentration of circulating estrogens. In the heart, SUR2A is the least expressed protein of all KATP channel-forming proteins. The consequence of this phenomenon is that the level of SUR2A is the main factor controlling the number of sarcolemmal KATP channels. Estrogens specifically up-regulate SUR2A and govern the number of sarcolemmal K(ATP) channels, and this may explain the effect of decreasing estrogen levels on the heart. An age-dependent decrease in the number of sarcolemmal K(ATP) channels generates a cardiac phenotype more sensitive to ischaemia, which seems to be responsible for the ageing-associated decrease in myocardial tolerance to stress that occurs in elderly women.

• 出版日期2006-12