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)
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)
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)
Using the single electrode voltage-clamp technique, stage V and VIXenopus oocytes showed a Ba inward current (endogenous IBa) with a peak amplitude of −15±2 nA in a Cl and Na-free Ba methane sulphonate medium. When oocytes were injected with pregnant rat (18 days gestation) myometrium mRNA, an additional component of Ba current could be detected (exogenous(More)
Xenopus oocytes injected with embryonic guinea-pig brain mRNA expressed functional P2Y purinoceptors. Extracellular ATP stimulated in a dose-dependent manner a delayed Ca2+-dependent Cl− current component. Analysis of the interactions of ATP with compounds that affect Ca2+ fluxes through the plasma membrane or Ca2+ release from internal stores indicates(More)