Hypertonic activation of phospholemman in solitary rat hepatocytes in primary culture

AbstractUnder hypertonic conditions, solitary rat hepatocytes in primary culture shrink and subsequently exhibit a distinct regulatory volume increase (RVI). Reverse-transcribed polymerase chain reaction and 5′ and 3′ RACE (rapid amplification of cDNA ends) techniques reveal that these cells express phospholemman (PLM). In whole-cell recordings, the hypertonic activation of a channel is observed that resembles PLM with respect to unitary conductance (600–700 pS), gating pattern, and non-selectivity for Na+ over K+. In Xenopus oocytes expressing hepatocyte PLM, hypertonic stress induces a non-selective cation conductance and noise analysis reveals the activation of a channel with a unitary conductance of approximately 700 pS. These results suggest a role of PLM in the RVI of rat hepatocytes