This paper describes the interaction of apamin, a bee venom neurotoxin, with the mouse neuroblastoma cell membrane. Voltage-clamp analyses have shown that apamin at low concentrations specifically blocks the Ca2+-dependent K+ channel in differentiated neuroblastoma cells. Binding experiments with highly radiolabeled toxin indicate that the dissociation constant of the apamin-receptor complex in...

The aim of this study was to investigate whether apamin-sensitive K(+)channels play a role in the NO induced relaxation of the human pregnant myometrium. Concentration-response curves for sodium nitroprusside (SNP) (10(-9)-10(-4)M) were constructed in the absence and presence of 10(-8)M apamin and 10(-7)M charybdotoxin (CTX). Preincubation with apamin resulted in a significant attenuation of th...

Doughty, Joanne M., Frances Plane, and Philip D. Langton. Charybdotoxin and apamin block EDHF in rat mesenteric artery if selectively applied to the endothelium. Am. J. Physiol. 276 (Heart Circ. Physiol. 45): H1107–H1112, 1999.—In rat mesenteric artery, endothelium-derived hyperpolarizing factor (EDHF) is blocked by a combination of apamin and charybdotoxin (ChTX). The site of action of these t...

Parkinson's disease has traditionally been viewed as a motor disorder caused by the loss of dopamine (DA) neurons. However, emotional and cognitive syndromes can precede the onset of the motor deficits and provide an opportunity for therapeutic intervention. Potassium channels have recently emerged as potential new targets in the treatment of Parkinson's disease. The selective blockade of small...

Purinergic inhibitory neuromuscular transmission plays an important role in the control of intestinal motility. In most tissues this neurotransmission is apamin-sensitive, but recent studies in human colonic circular smooth muscle (CSM) suggest the presence of apamin-insensitive purinergic inhibitory junction potentials (IJPs). The current studies used conventional intracellular recordings on c...

Small conductance calcium-activated potassium channels (KCa2.1,2.2,2.3) are blocked with high affinity by both peptide toxins (e.g. apamin) and small molecule blockers (e.g. UCL 1848). In electrophysiological experiments, apamin shows subtype selectivity with IC50s of ∼100 pM and ∼1 nM for block KCa2.2 and KCa2.3 respectively. In binding studies, however, apamin appears not to discriminate betw...

In area CA1 of hippocampal slices, a single 1-sec train of 100-Hz stimulation generally triggers a short-lasting long-term potentiation (S-LTP) of 1-2 h. Here, we found that when such a train was applied 45 min after application of the small conductance Ca(2+)-activated K(+ )(SK) channel blocker apamin, it induced a long-lasting LTP (L-LTP) of several hours, instead of an S-LTP. Apamin-induced ...

Sharp electrode current-clamp recording techniques were used to characterize the response of nigral dopamine (DA)-containing neurons in rat brain slices to injected current pulses applied in the presence of TTX (2 microM) and under conditions in which apamin-sensitive Ca2+-activated K+ channels were blocked. Addition of apamin (100-300 nM) to perfusion solutions containing TTX blocked the pacem...

BACKGROUND Apamin-sensitive K currents (I(KAS)) are upregulated in heart failure. We hypothesize that apamin can flatten action potential duration restitution (APDR) curve and can reduce ventricular fibrillation duration in failing ventricles. METHODS AND RESULTS We simultaneously mapped membrane potential and intracellular Ca (Ca(i)) in 7 rabbit hearts with pacing-induced heart failure and i...

The involvement of nitric oxide and ATP in both spontaneous and electrically-induced nonadrenergic noncholinergic (NANC) motor activity with special interest in the apamin-sensitive mechanisms was studied in a guinea pig ileum model. Depending on the concentration (0.1 or 1 micromol/l), apamin, a blocker of the calcium-activated potassium channels and antagonist of ATP action, induced either TT...