Because the electrophysiological effects of pituitary adenylate cyclase-activating polypeptide (PACAP) on the heart are little known, we studied the regulation of the atrial ATP-sensitive K(+) (K(ATP)) current by PACAP on primary cultured neonatal rat atrial myocytes. PACAP-38 stimulates cAMP production with EC(50) = 0.28 nmol/l (r = 0.92, P < 0.02). PACAP-38 and PACAP-27 (10 nmol/l) have simil...

Effects of cytochalasins B and D (CB, CD) were examined for the contractions of the longitudinal myometrium of pregnant rat exposed to Krebs solution, 40 mM K Krebs, and Ca-free (40 mM K) solution containing 5 mM Mg. The Ca-free contraction was evoked by applying 3 mM ATP. Application of CB caused a prompt inhibition of the contractions: 3 microM CB depressed the twitch contraction generated in...

Resealed human red blood cell ghosts were prepared to contain a range of ADP concentrations at fixed ATP concentrations and vice versa. ATP/ADP ratios ranging from approximately 0.2 to 50 were set and maintained (for up to 45 min) in this system. ATP and ADP concentrations were controlled by the addition of either a phosphoarginine- or phosphocreatine-based regenerating system. Ouabain-sensitiv...

BACKGROUND Pregabalin is an anticonvulsant and analgesic agent that interacts selectively with the voltage-sensitive-Ca(2+)-channel alpha-2-delta subunit. The aim of this study was to evaluate whether the analgesic action of intrathecal (IT) pregabalin is associated with K(ATP) channels in the rat formalin test. METHODS IT PE-10 catheters were implanted in male Sprague-Dawley rats (250-300 g)...

The mechanism by which ATP-sensitive K 1 (K ATP ) channels open in the presence of inhibitory concentrations of ATP remains unknown. Herein, using a four-state kinetic model, we found that the nucleotide diphosphate UDP directed cardiac K ATP channels to operate within intraburst transitions. These transitions are not targeted by ATP, nor the structurally unrelated sulfonylurea glyburide, which...

introduction: we have recently reported the presence of two potassium currents with 598 and 368 ps conductance in the rough endoplasmic reticulum (rer) membrane. the 598 ps channel was voltage dependent and atp sensitive. however, the 368 ps channel was rarely observed and its identity remained obscure. since cationic channels in intracellular organelles such as mitochondria and rer play import...

We investigated on the mechanism responsible for the reduced ATP-sensitive K(+)(K(ATP)) channel activity recorded from skeletal muscle of K(+)-depleted rats. Patch-clamp and gene expression measurements of K(ATP) channel subunits were performed. A down-regulation of the K(ATP) channel subunits Kir6.2(-70%) and SUR2A(-46%) in skeletal muscles of K(+)-depleted rats but no changes in the expressio...

Isolated kidney mitochondria swell when incubated in hyposmotic solutions containing K+ salts in a manner inhibited by ATP, ADP, 5-hydroxydecanoate, and glibenclamide and stimulated by GTP and diazoxide. These results suggest the existence of ATP-sensitive K+ channels in these mitochondria, similar to those previously described in heart, liver, and brain. Renal mitochondrial ATP-sensitive K+ up...

BACKGROUND Recent studies have implicated mitochondrial ATP-sensitive potassium (K(ATP)) channels in the cardioprotective effects of ischemic preconditioning. The present study used a model of prolonged cold heart storage to assess whether the mitochondrial K(ATP) opener diazoxide could reproduce the protection conferred by ischemic preconditioning. METHODS AND RESULTS Fifty-four isolated rat...