The Journal of physiology
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The Journal of physiology · Dec 2001
Modulation of GABA(A) receptor channel gating by pentobarbital.
1. We have studied the kinetic properties of channel gating of recombinant alpha 1 beta 2 gamma 2L GABA(A) receptors transiently expressed in human embryonic kidney 293 cells, using the cell-attached, single-channel patch-clamp technique. The receptors were activated by GABA, beta-alanine or piperidine-4-sulfonic acid (P4S), and the effects of pentobarbital (PB) on single-channel activity were examined. 2. ⋯ The actions on receptors activated by P4S or beta-alanine are also broadly consistent with this idea. However, the changes in open-time distributions caused by PB appear to be more complex. Possible explanations of the effects of PB on gating by different agonists are considered.
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The Journal of physiology · Dec 2001
Hypersensitivity of pulmonary C fibre afferents induced by cationic proteins in the rat.
1. Airway administration of synthetic cationic proteins, poly-L-lysine (PLL) and poly-L-arginine (PLA), is known to induce bronchial hyper-responsiveness, and an involvement of bronchopulmonary C fibre activation has been suggested. In this study we investigated the effects of PLL and PLA on single-unit pulmonary vagal C fibre afferents in anaesthetized, open-chest rats. 2. ⋯ In conclusion, I. T. instillation of synthetic cationic proteins causes an intense stimulatory effect on pulmonary C fibres and potentiates their sensitivities to both lung inflation and chemical stimuli. These effects are probably generated by an interaction between the cationic charges carried by these proteins and the airway mucosa.
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The Journal of physiology · Dec 2001
Electrophysiological analysis of the negative chronotropic effect of endothelin-1 in rabbit sinoatrial node cells.
1. Electrophysiological effects of endothelin-1 (ET-1) were studied in rabbit sinoatrial node (SAN) using conventional microelectrode and whole-cell voltage and current recordings. 2. In rabbit SAN, RT-PCR detected ET(A) endothelin receptor mRNA. ⋯ The hyperpolarisation-activated current (I(f)), observed exclusively in spindle-shaped cells, was significantly increased by ET-1 at membrane potentials between -74.7 and -84.7 mV whereas it was significantly decreased at more negative potentials. ET-1 significantly decreased the slope of the current-voltage (I-V) relation of the I(f) tail without changing its half-maximum voltage. 6. The overall negative chronotropic influence of ET-1 on the whole rabbit SAN is interpreted as resulting from the integration of its different actions on spindle- and rod-shaped SAN cells through electrotonic interaction.