Myocellular sodium homeostasis is commonly disrupted during critical illness for unknown reasons. Recent data suggest that changes in intracellular sodium content and the amount of ATP provided by glycolysis are closely related. The role of glycolysis and oxidative phosphorylation in providing fuel to the Na(+)-K(+) pump was investigated in resting rat extensor digitorum longus muscles incubated at 30 degrees C for 1 h. Oxidative inhibition with carbonyl cyanide m-chlorophenylhydrazone, known as CCCP (0.2 microM), or by hypooxygenation did not alter myocellular sodium or potassium content ([Na(+)](i), [K(+)](i), respectively), whereas treatment with iodoacetic acid (0.3 mM), which effectively blocked glycolysis, dramatically increased [Na(+)](i) and the [Na(+)](i)/[K(+)](i) ratio. Experiments using ouabain and measurements of myocellular high-energy phosphates indicate that Na(+)-K(+)-ATPase activity is only impaired when glycolysis is inhibited. The data suggest that normal glycolysis is required to regulate intracellular sodium in fast-twitch skeletal muscles, because it is the predominant source of the fuel for the Na(+)-K(+)-ATPase.

Recruitment of the barnacle Balanus amphitrite into a macrofouling community was examined in a semi-enclosed coastal environment (Hamana Bay, Japan), where water exchange with the adjacent open sea is very limited. The recruitment period of these barnacles was shorter than the period in which this species can breed and in which the cirripede larvae are present in the environment. Rearing of B. amphitrite larvae at different temperatures (15 to 30°C) and salinities (10, 20 and 30%) revealed that its development is euryhaline. The ~nfluence of temperature was found to be greatest on the second instar. Mortality rates at 15°C temperature ranged from 43 % (30% salinity) to 99% (10%0 salinity). Rearlng experiments indicated that larvae released to the environment during autumn and winter failed to establish themselves in the macrofouling community because of adverse environmental conditions. These results also show that loss of planktonic larvae through starvation and rnisrouting may well be the main cause of reproductive loss.

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