Background: Lem3p-Dnf1p and Lem3p-Dnf2p are phospholipid flippases that generate phospholipid asymmetry in yeast. Results:The tryptophan permease Tat2p is missorted from the trans-Golgi network to the vacuole in the lem3⌬ mutant. Conclusion: Phospholipid asymmetry supports plasma membrane transport of Tat2p by inhibiting its improper ubiquitination at the trans-Golgi network. Significance: Phospholipid asymmetry may be involved in proper sorting of membrane proteins.

Nitric oxide (NO) has been known to play various functional and pathological roles as an intracellular or intercellular messenger in the heart. In this study, we investigated whether NO produced during ischemia was involved in the coordination of ATP supply and demand, and also in protection from cell death using cultured cardiac myocytes. Unexpectedly, the survival rate of myocytes for 3 h simulated ischemia (SI) was increased as compared with that for 2 h SI at 24 h after reperfusion. The cellular ATP level at 3 h after the start of SI was increased compared with that at 2 h, and was almost the same as that before the start of SI. The cellular ATP level at 3 h SI was significantly reduced by either the inhibition of nitric oxide synthase (NOS) or scavenging of NO. Either the inhibition of NOS or the scavenging of NO during SI for 3 h also resulted in a significant decrease in the survival rate of myocytes.Immunocytochemical and Western blot analyses revealed that the expression of nNOS was most evident in cardiac myocytes, but no significant change was observed in the expression of all three NOS isoforms at 2 h SI and at 3 h SI. The fluorescent intensity of DAF-FM was significantly increased at 3 h SI as compared with that at 2 h SI, and 2 the increase in DAF fluorescence during SI was almost completely suppressed by treatment with L-VNIO, a potent specific inhibitor of nNOS. In addition, treatment with L-VNIO decreased the cellular ATP level and survival rate. This study suggested that the enhanced production of NO was critical in balancing ATP supply and demand during ischemia, and also in protecting cells from ischemia/reperfusion injury.

SummaryIsolated and cultured neonatal cardiac myocytes contract spontaneously and cyclically.The contraction rhythms of two isolated cardiac myocytes, each of which beats at different frequencies at first, become synchronized after the establishment of mutual contacts, suggesting that mutual entrainment occurs due to electrical and/or mechanical interactions between two myocytes. The intracellular concentration of free Ca 2+ also changes rhythmically in association with the rhythmic contraction of myocytes (Ca

Cultured cardiac myocytes from neonatal rats show spontaneous and rhythmic contractions.The intracellular concentration of free Ca 2+ also changes rhythmically associated with the rhythmic contraction of myocytes (Ca 2+ oscillation). This study aims to elucidate whether spontaneous rhythmic contraction affects the dynamics of intracellular Ca

1 SummaryThe heart functions as a syncytium of cardiac myocytes and surrounding supportive non-myocytes such as fibroblasts. There is a possibility that a variety of non-myocyte-derived factors affect the maturation of cardiac