Michael Korth

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Large conductance voltage- and Ca(2+)-activated potassium channels (BK channels) are important feedback regulators in excitable cells and are potently regulated by protein kinases. The present study reveals a dual role of protein kinase C (PKC) on BK channel regulation. Phosphorylation of S(695) by PKC, located between the two regulators of K(+) conductance(More)
The large-conductance, voltage-dependent and Ca(2+)-dependent K(+) (BK) channel links membrane depolarization and local increases in cytosolic free Ca(2+) to hyperpolarizing K(+) outward currents, thereby controlling smooth muscle contractility. Constitutive deletion of the BK channel in mice (BK(-/-)) leads to an overactive bladder associated with(More)
Large-conductance, calcium- and voltage-gated potassium (BK) channels play an important role in cellular excitability by controlling membrane potential and calcium influx. The stress axis regulated exon (STREX) at splice site 2 inverts BK channel regulation by protein kinase A (PKA) from stimulatory to inhibitory. Here we show that palmitoylation of STREX(More)
 The cloned BK channel α subunit from human myometrium was stably expressed in Chinese hamster ovary cells, either alone (CHOα cells) or in combination with the auxiliary β subunit (CHOα+β cells). We studied basic channel properties and the effects of cGMP- and cAMP-dependent protein kinases on the BK channel activity. Coexpression of α and β subunits(More)
1. The inotropic effects of (±)-isoprenaline and several phosphodiesterase (PDE)-inhibitors were studied in isometrically contracting guinea-pig papillary muscles driven at a rate of 0.2 Hz. The maximal positive inotropic effect of isoprenaline (ΔF c=2.2 g;n=7) corresponded to that of 1-methyl, 3-isobutylxanthine (IBMX) and theophylline (ΔF c=2.1 and 2.2 g,(More)
The aim of the present study was to determine the mechanism of the positive inotropic effect of carbachol on ventricular myocardium. Carbachol produced a concentration-dependent (0.1 to 300 μmol/l) increase in contraction force on the catecholamine-depleted papillary muscle of the guinea pig without affecting the normal action potential or the slow action(More)
1. The inotropic effects of benzyl-and substituted benzyl triesters of cyclic AMP and cyclic GMP were studied in isometrically contracting guineapig papillary muscles driven at a rate of 0.2 Hz. 2. The triesters of cyclic AMP produced marked concentration-dependent positive inotropic effects. The maximum increase of contraction force (ΔF c) was 2.2 g (n=5)(More)
Airway smooth muscle is richly endowed with muscarinic receptors of the M(2) and M(3) subtype. Stimulation of these receptors inhibits large conductance calcium-activated K(+) (BK) channels, a negative feed back regulator, in a pertussis toxin-sensitive manner and thus facilitates contraction. The underlying mechanism, however, is unknown. We therefore(More)
The mRNAs of MT1 and MT2 melatonin receptors are present in cells from nonpregnant (NPM) and pregnant (PM) rat myometrium. To investigate the coupling of melatonin receptors to Gq- and Gi-type of heterotrimeric G proteins, we analyzed the activity of large-conductance Ca2+-activated K+ (BKCa) channels, the expression of which in the uterus is confined to(More)
Regulation of protein phosphorylation by kinases and phosphatases is involved in many signaling pathways in mammalian cells. In contrast to prokaryotes and lower eukaryotes a role for the reversible phosphorylation of histidine residues is just emerging. The β subunit of heterotrimeric G proteins, the metabolic enzyme adenosine 5'-triphosphate-citrate lyase(More)