P. Guilbault

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A novel human-voltage-dependent-calcium-channel (VDCC) beta subunit was isolated from a 9-week-old human total-embryo cDNA library. Of the four genes encoding beta-subunit isoforms that have been identified in animal species, this isoform shares strong similarity with the rat and rabbit beta 3-related gene product and is referred to here as H beta 3(More)
Biphasic contractions were produced in guinea pig papillary muscle by inducing partial depolarization in a K+ -rich solution (22 mM) containing 10(-6) M isoproterenol. However, when the same conditions were applied to frog and rat, monophasic contractions were obtained. In the case of guinea pig, an increase in the beating frequency produced an increase in(More)
The double electrode voltage-clamp technique was used to study voltage-dependent Ca(2+) channels in Pleurodeles oocytes. From a holding potential of -80 mV, Ba-current (IBa) (recorded in Cl-free solution, Ba(2+ = 40 mM) activated at -36.7 +/- 4 mV, peaked at -11.6 +/- 4 mV and reversed at 55 +/- 7 mV (n = 24). This current activated slowly (rise time was(More)
Voltage clamp technique was used to study macroscopic ionic currents in Rana esculenta oocytes. Depolarization steps led to the activation of a single type of outward current (I out) when contaminant potassium and calcium-dependent chloride currents were pharmacologically inhibited. The voltage threshold of I out activation was 10 mV and this current, which(More)
In normal medium supplemented with 10 mM tetraethylammonium chloride (TEACl), membrane depolarizations of immature Rana esculenta oocytes elicited an oscillatory outward current associated with a voltage-dependent H+ current (IH+). The voltage threshold of these oscillations was 22 +/- 5 (n = 10). The oscillations were blocked by intracellular injection of(More)
The effects of cyclic AMP (cAMP) and cyclic GMP (cGMP) on dihydropyridine sensitive Ca2+ channels were investigated under voltage-clamp in defolliculated Pleurodeles oocytes. Intracellular injection of cAMP or extracellular application of the permeable cAMP analogue (8-Bromo cAMP, 8Br-cAMP) decreased the Ba current (IBa). This effect on IBa was blocked by(More)
Two inward currents were observed in crayfish muscle membrane during depolarization steps by the method described by Adrian et al. (1970). Under voltage clamp conditions, hyperpolarization steps elicited a large current (leak current If), associated with an inward voltage dependent current. This inward current was inhibited by niflumic acid (NA), a drug(More)
Using the whole cell voltage-clamp technique and a C1 free and Na free Ba methane sulfonate solution, stage V and VI Xenopus oocytes demonstrated a Ba current (endogenous component) with a peak amplitude average of 6 nA (6 +/- 2 nA). When oocytes were injected with crustacean skeletal muscle mRNA, an additional component of IBa could be detected (exogenous(More)
Biphasic contractions were obtained in guinea-pig papillary muscle by inducing partial depolarization in K+-rich solution (17 mM) in the presence of 0.3 microM isoproterenol. Mn2+ ions inhibited the two components of contraction in a similar way. Nifedipine and particularly Cd2+ ions specifically inhibited the second component of contraction. Isoproterenol(More)