In the central nervous system, small conductance calcium-activated potassium channels (SK) are important for the generation of the afterhyperpolarisation that follows single or trains of action potentials. Three SK channels have been cloned (SKI, SK2 and SK3), which are selectively blocked by the venom toxin apamin and present distinct pharmacological properties. The principal aim of this work ...

Acetylcholine (ACh) is a neurotransmitter critical for normal cognition. Here we demonstrate heterogeneity of cholinergic signaling in neocortical neurons in the rat prefrontal, somatosensory, and visual cortex. Focal ACh application (100 muM) inhibited layer 5 pyramidal neurons in all cortical areas via activation of an apamin-sensitive SK-type calcium-activated potassium conductance. Choliner...

BACKGROUND AND PURPOSE The role of SK(Ca) and IK(Ca) channels in myogenic tone and endothelium-derived hyperpolarizing factor (EDHF) responsiveness was investigated under control conditions and after ischemia and reperfusion in parenchymal arterioles (PA) versus middle cerebral arteries (MCA). METHODS MCA and PA were dissected from male Wistar rats that were ischemic for 1 hour with 24 hours ...

The mechanism by which acetylcholine (ACh) decreases systemic arterial pressure and hindlimb vascular resistance was investigated in the anesthetized rat. ACh injections caused dose-dependent decreases in systemic arterial pressure and hindlimb vascular resistance. N(omega)-nitro-L-arginine methyl ester (L-NAME) had little effect on the magnitude of depressor and vasodilator responses but decre...

Striatal cholinergic interneurons recorded in slices exhibit three different firing patterns: rhythmic single spiking, irregular bursting, and rhythmic bursting. The rhythmic single-spiking pattern is governed mainly by a prominent brief afterhyperpolarization (mAHP) that follows single spikes. The mAHP arises from an apamin-sensitive calcium-dependent potassium current. A slower AHP (sAHP), al...

Although small-conductance Ca(2+)-activated K(+) (SK) channels and various types of voltage-gated Ca(2+) (Cav) channels have been described in midbrain dopaminergic neurons, the nature of their interactions is unclear. More particularly, the role of various Cav channel types in either promoting irregularity of firing (by generating an inward current during SK channel blockade) or promoting regu...

We previously demonstrated that stimulation of proteinase-activated receptor-2 (PAR-2) by SLIGRL-NH(2) elicits afferent arteriolar vasodilation, in part, by elaborating nitric oxide (NO), suggesting an endothelium-dependent mechanism (Trottier G, Hollenberg M, Wang X, Gui Y, Loutzenhiser K, and Loutzenhiser R. Am J Physiol Renal Physiol 282: F891-F897, 2002). In the present study, we characteri...

Background—K channel activation in vascular smooth muscle cells (VSMCs) plays a key role in regulating vascular tone. It has been proposed that endothelium-derived hyperpolarizing factor (EDHF) contributes to microvascular dilation more than nitric oxide (NO) does. Whether hyperpolarization is important for coronary arteriolar dilation in humans is not known. Bradykinin (BK), an endogenous vaso...

Seutin, Vincent, Laurent Massotte, Jacqueline Scuvée-Moreau, ena observed in our study were due to the anesthetic, some (n Å 16) neonatal rats were killed without prior anesthesia. The other and Albert Dresse. Spontaneous apamin-sensitive hyperpolarizations in dopaminergic neurons of neonatal rats. J. Neurophysiol. animals were anesthetized with halothane. All animals were decapitated. 80: 3361...