The binding of oxygen by the haemocyanin of the gastropod Lymnaea stagnalis was studied by equilibrium and kinetic methods. The studies were performed under conditions in which the haemocyanin molecule was in the native state. Over the pH range 6.8-7.6, in the presence of 10mM-CaCl2 the haemocyanin bound O2 cooperatively. Over this pH range the haemocyanin molecule displayed a normal Bohr effec...

Both Mg2+ and Ca2+ have been implicated as having roles in the pathomechanisms of cerebral ischemia. To further study the effects of these ions on postischemic histologic outcome, fasted rats were given one of three intravenous infusions: 5.0 mmol/kg MgCl2, 5.0 mmol/kg MgCl2 + 0.035 units/kg regular insulin, or 1.0 mmol/kg CaCl2. This resulted in elevated plasma Mg2+ or Ca2+ concentrations in t...

The intracellular Ca2+ stores and the mechanisms of Ca2+ entry produced by norepinephrine (NE) were investigated in small mesenteric resistance arteries of the rat. In Ca2+-free medium, NE (10 μM) elicited a transient increase in both intracellular free Ca2+concentration ([Ca2+]i) and tension that were both drastically reduced by caffeine and only partially reduced by the two sarco(endo)plasmic...

The slow voltage dependent calcium channels have been described in skeletal muscle fibres of adult frogs and rats (Sanchez and Stefani 1978; Donaldson and Beam 1983). Some data have suggested that they may participate in excitationcontraction coupling (ECC) (Beam et al. 1986; Ildefonse et al. 1985; Rios et al. 1986). However, some other investigations have shown the independence of ?"'' tion of...

The objectives of this study were to determine the extent to which pH and ionic strength influence mu- and m-calpain activity and the inhibition of calpains by calpastatin. Calpastatin, mu-calpain, and m-calpain were purified from at-death porcine semimembranosus. Mu-calpain or m-calpain (0.45 U) were incubated with the calpain substrate Suc-Leu-Leu-Val-Tyr-7-amino-4-methyl coumarin in the pres...

We present the first systematic investigation of Tc(iv) solubility, hydrolysis and speciation in dilute to concentrated NaCl, MgCl2 and CaCl2 systems, and comprehensive thermodynamic and activity models for the system Tc(4+)-H(+)-Na(+)-Mg(2+)-Ca(2+)-OH(-)-Cl(-)-H2O using both SIT and Pitzer approaches. The results are advancing the fundamental scientific understanding of Tc(iv) solution chemist...