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High pressure does not cause unfolding of secondary structure units in sperm whale myoglobin but rather smaller conformational changes that provide pathways for water diffusion.

The impact of high pressure on Lactobacillus plantarum growth at pH 5.0 and 7.0 was examined. The classical inactivation kinetics were compared with a number of events related to the acid-base physiology of the cell. Findings showed that cells grown at pH 5.0 were more resistant to pressures than cells grown in pH 7.0. After pressure treatment, adenosine triphosphatase (ATPase) activity decreased and acid efflux was impaired. No morphological changes of the membrane were observed although functions related to the membrane-bound ATPase activity were impaired.

A study of the effects of pressure and adenylylation state on dodecamer stacking in the supramolecular self-assembly of Escherichia coli glutamine synthetase suggests that the bimolecular rate constant of the adenylylated enzyme is lower than that of the unadenylylated enzyme. Both enzymes have identical activation enthalpies, indicating that entropic factors contribute to the differences in stacking rates. Stacking in both the enzymes is suppressed by hydrostatic pressure. Adenylylation improves the rate constants for the forward and reverse reactions.

Results reveal that the homotrimeric vesicular stomatitis virus G protein undergoes pressure-induced conformational change that preserves the fusion properties of the virus as seen in an increase in light scattering. This represents a 'fusion-intermediate state' and contain minor changes in secondary structure.

Hines, Tina. Baroreceptor afferent discharge in the pregnant rat. Am J Physiol Regulatory Integrative Comp Physiol 278: R1433-R1440, 2000.--Pregnancy is associated with blunted reflex responses to cardiac and arterial baroreceptor stimulation. We tested the hypothesis that arterial baroreceptor afferent discharge is attenuated in response to a pressure stimulus in pregnant rats. Multifiber aortic depressor nerve activity (ADNA), mean arterial pressure (MAP), and heart rate were measured in anesthetized (pentobarbital sodium, 35 mg/kg ip) late-pregnant and virgin rats in response to increases [phenylephrine (PE), 1.5-24 [micro]g [multiplied by] [kg.sup.-1] [multiplied by] [min.sup.-1] and 1-16 [micro]g/kg] and decreases [sodium nitroprusside (SNP), 5-80 [micro]g [multiplied by] [kg.sup.-1] [multiplied by] [min.sup.-1] and 0.05-16 [micro]g/kg] in MAP. Resting MAP was lower in pregnant rats, but changes in MAP were similar to those in virgin rats during both PE and SNP administration. ADNA was significantly attenuated in pregnant animals during both PE and SNP infusions (P [is less than] 0.05) due to a more rapid adaptation to the pressure stimulus. Bolus drug administration evoked similar changes in MAP and ADNA in both groups; however, the maximum decrease in ADNA was achieved at the lowest dose of SNP in pregnant rats. Thus baroreceptor afferent discharge is attenuated in pregnant rats, and this involves a more rapid adaptation to a pressure stimulus. baroreflex; aortic depressor nerve; phenylephrine; nitroprusside