Effects of adrenaline (ADR) and the dihydropyridine Ca channel agonist CGP-IOS were studied on twitch and tetanic contractions of isolated tonic muscle fibres or small muscle fibre bundles containing tonic fibres of the frog Rana temporaria. Tetanization caused a gradual increase of tension between 10 and 70 Hz. CGP-IOS produced an increase in twitch amplitude. After CGP-IOS administration (2 x...

We propose a general reaction mechanism for the pyridine (Py)-catalyzed reduction of CO2 over GaP(111), CdTe(111), and CuInS2(112) photoelectrode surfaces. This mechanism proceeds via formation of a surface-bound dihydropyridine (DHP) analogue, which is a newly postulated intermediate in the Py-catalyzed mechanism. Using density functional theory, we calculate the standard reduction potential r...

The present study reports a microwave-assisted method for the synthesis of twelve novel tricyclic 1,4-dihydropyridine derivatives in which dimethyl-substituted cyclohexane and / or tetrahydrothiophene rings are fused to the DHP ring. The structures of the compounds were confirmed by spectral methods and elemental analysis. The potassium channel opening effects of the compounds were determined o...

Whole-cell patch clamp recording was used to characterize calcium currents in Purkinje cells dissociated from the cerebellar vermis of 1-3-week postnatal rats. A subset of Purkinje cells had a low-threshold, transient current similar to the T-type current in peripheral neurons. All Purkinje cells had a high-threshold, slowly inactivating current. Only a small component of the high-threshold cur...

The transmembrane segment IIIS5 of the L-type calcium channel alpha1 subunit participates in the formation of the 1,4-dihydropyridine (DHP) interaction domain (Grabner, M., Wang, Z., Hering, S., Striessnig, J., and Glossmann, H. (1996) Neuron 16, 207-218). We applied mutational analysis to identify amino acid residues within this segment that contribute to DHP sensitivity. DHP agonist and antag...

We have purified putative L-type Ca2+ channels from chick heart by virtue of their associated high affinity receptors for the Ca2+ channel effectors, dihydropyridines (DHPs), and phenylalkylamines (PAAs). A peptide of 185,000-190,000 daltons was found to comigrate with the peak of DHP binding activity during purification through two successive cycles of lectin affinity chromatography and sucros...

Prior observations have raised the possibility that dihydropyridine (DHP) agonists directly affect the sarcoplasmic reticulum (SR) cardiac Ca(2+) release channel [i.e., ryanodine receptor (RyR)]. In single-channel recordings of purified canine cardiac RyR, both DHP agonists (-)-BAY K 8644 and (+)-SDZ202-791 increased the open probability of the RyR when added to the cytoplasmic face of the chan...

As a continuous research for discovery of new COX-2 inhibitors, chemical synthesis, in vitro biological activity and molecular docking study of anew group of 1,4-dihydropyridine (DHP) derivatives were presented. Novel synthesized compounds possessing a COX-2 SO2Me pharmacophore at the para position of C-4 phenyl ring, different hydrophobic groups (R1) at C-2 position and alkoxycarbonyl groups (...

Hantzsch condensation of two equivalents of methyl-3-aminocrotonate with (m- and p)-methoxybenzaldehyde afforded the expected products 2,6-dimethyl-3,5-dimethoxycarbonyl-4-(m-methoxyphenyl)-1,4-dihydropyridine and 2,6-dimethyl-3,5-dimethoxycarbonyl-4-(p-methoxyphenyl)-1,4-dihydropyridine, whereas o-methoxy-benzaldehyde produced mainly 1-amino-2-methoxycarbonyl-3,5-bis(o-methoxy-phenyl)-4-oxa-cy...

We compared the density of dihydropyridine (DHP) receptor sites with the density of functional L-type calcium channels in ventricular myocytes from chick heart at embryonic day 11. DHP receptors were quantified by using the DHP antagonist (+)-[3H]PN200-110 and by competition binding with the agonist Bay K 8644. The number of agonist and antagonist binding sites per ventricle was similar (250 +/...