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Age and hypertension contribute significantly to cardiac morbidity and mortality, however the importance of each during the progression of hypertrophy is unclear. This investigation examined the effect of age and hypertension on Ca(2+) handling in rat ventricular myocytes by comparing a genetic model of hypertension and cardiac hypertrophy (spontaneously hypertensive rat, SHR) with its normotensive control (Wistar-Kyoto rat, WKY) at 5 and 8 months of age. Experiments were performed on single left ventricular myocytes isolated from SHR or WKY hearts. Intracellular Ca(2+) was measured optically using fura-2 or fluo-3. SHR myocytes had a significantly larger cell width and volume and a significantly decreased cell length/width ratio at 5 and 8 months compared to normotensive controls. Age had no effect on cell length, width, volume or the length/width ratio. Ca(2+) transient amplitude, sarcoplasmic reticulum (SR) Ca(2+) content and contraction amplitude were unaffected by age or hypertrophy. However at 8 months the contribution of the SR to Ca(2+) uptake during relaxation decreased, with a concomitant increase in the contribution of Na(+)/Ca(2+) exchanger (NCX) function to relaxation, in SHR and WKY myocytes. The incidence of non-synchronous SR Ca(2+) release decreased with age but not hypertrophy in SHR and WKY myocytes. These results show that the changes in Ca(2+) handling observed during progression of mild hypertrophy in SHR are the same as those that occur during ageing in normotensive control animals and can, therefore, be ascribed to maturation rather than hypertrophy.

Sugar beet cells grown in liquid suspension culture entered the stationary phase on day 17 of the batch culture cycle as a consequence of nutrient depletion. Between days 17 and 19 the cells exhibited a number of marked changes in RNA and protein metabolism characteristic of entry into a quiescent or G0 state. Protein synthesis declined considerably and very few polypeptides incorporated sufficient radioactively labelled methionine to be detected by fluorography following polyacrylamide gel electrophoresis (SDS-PAGE). There was a marked decrease in protein half life during the stationary phase and this was accompanied by a rise in protease activity. RNA synthesis also decreased to

Early CHARMM all-atom force fields showed transition temperatures well above the experimental value of 315K. We simulated 100 ns for DPH and TMA-DPH dyes in DPPC lipid bilayers at atmospheric pressure and temperatures from 300-330K in 5K increments. Shifts were observed between 305K and 315K in area-per-headgroup, bilayer thickness, lipid-tail order parameters, and steady state dye fluorescence anisotropy. Dye effects on these membrane properties were negligible.