BACKGROUND Purkinje cells (PCs) are important in cardiac arrhythmogenesis. Whether small-conductance calcium-activated potassium (SK) channels are present in PCs remains unclear. We tested the hypotheses that subtype 2 SK (SK2) channel proteins and apamin-sensitive SK currents are abundantly present in PCs. METHODS AND RESULTS We studied 25 normal rabbit ventricles, including 13 patch-clamp s...

Recently, we showed that caveolin-1 (cav1) knockout mice (Cav1(-/-) mice) have impaired nitric oxide (NO) function in the longitudinal muscle (LM) layer of the small intestine. The defect was a reduced responsiveness of the muscles to NO compensated by an increase in the function of apamin-sensitive, nonadrenergic, noncholinergic (NANC) mediators. In the present study, we examined similarly the...

Nagayama, Takahiro, Yasuo Fukushima, Hirohiko Hikichi, Makoto Yoshida, Mizue Suzuki-Kusaba, Hiroaki Hisa, Tomohiko Kimura, and Susumu Satoh. Interaction of SKCa channels and L-type Ca 21 channels in catecholamine secretion in the rat adrenal gland. Am J Physiol Regulatory Integrative Comp Physiol 279: R1731–R1736, 2000.—We elucidated the interaction of small-conductance Ca-activated K (SKCa) ch...

The effects of tetraethylammonium, apamin, 4-aminopyridine and holding potential on the phenylephrine-evoked outward currents in dispersed smooth muscle cells of the rabbit taenia caeci were analyzed using the whole cell patch clamp method. Phenylephrine (10 mumol/l) under the double sucrose gap condition, substantially hyperpolarized the smooth muscle membrane and reduced the input membrane re...

A peptide NTH-18 was synthesized in which a N-terminal helix is stabilised by two crossed disulfide bonds to a C-terminal extension. The design was inspired by the structure of the neurotoxic peptide apamin, which has previously been used to stabilise helices in miniature enzymes. CD- and NMR-spectroscopy indicated that NTH-18 adopted a fold similar to that found in apamin. However, the arrange...

Small airway and vessels play a critical role in chronic airway and pulmonary vascular diseases, but their pharmacology has not been well characterised. We have studied airway and vascular responses in rat lung slices and separately in vitro using myography. In lung slices, under basal conditions, acetylcholine contracted airways, but had no vascular effect. The thromboxane mimetic, U46619 cont...

Taicatoxin, isolated from the venom of the Australian taipan snake Oxyuranus scutellatus, has been previously regarded as a specific blocker of high threshold Ca channels in heart. Here we show that taicatoxin (in contrast to a range of other Ca channel blockers) interacts with apamin-sensitive, small conductance, Caactivated potassium channels on both chromaffin cells and in the brain. Taicato...

The electrophysiological properties of smooth muscle in the murine lower oesophageal sphincter (LOS) were investigated by intracellular microelectrode recording. Inhibitory junction potentials (IJPs) evoked by trains of field stimulation (30 V, 0.2-0.3 ms, 10 stimuli at 1-50 Hz) were observed in the murine LOS in the presence of atropine (1 microM) and nifedipine (1 microM). The IJP consists of...

The spontaneous discharge patterns of developing retinal ganglion cells are thought to play a crucial role in the refinement of early retinofugal projections. To investigate the contributions of intrinsic membrane properties to the spontaneous activity of developing ganglion cells, we assessed the effects of blocking large and small calcium-activated potassium conductances on the temporal patte...