Phospholipid-Calcium Relations at the Sarcolemma of the Cardiac Cell
The mammalian heart controls its force development by two general mechanisms: (1) The Frank-Starling response to changing preload which involves a change in diastolic fiber length, and (2) a change of contractile state in which force changes without a primary change in the relation of sarcomeric myofilaments to each other. There is evidence (Allen and Kentish, 1985) that the Frank-Starling response might involve changes in intracellular calcium (Ca) distribution and/or myofilament sensitivity that may affect force, but the primary event is the length change. In contrast, the second mechanism, change in contractile state, is primarily dependent on alterations in cellular Ca flux and exchange. The characteristics of this flux and exchange have been the focus of my laboratory at UCLA for the past 20 years. This paper will present a brief review of the current state of our knowledge with emphasis on the possible role of phospholipid in the sarcolemmal membrane in the regulation of Ca binding and exchange.
KeywordsContractile Force Contractile State Diffuse Double Layer Sarcolemmal Membrane Exchangeable Pool
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