Circadian pacemaking in suprachiasmatic nucleus (SCN) neurons revolves around transcriptional/posttranslational feedback loops, driven by protein products of "clock" genes. These loops are synchronized and sustained by intercellular signaling, involving vasoactive intestinal peptide (VIP) via its VPAC2 receptor, which positively regulates cAMP synthesis. In turn, SCN cells communicate circadian...

The different HCN elimination pathways from vinyl cyanide (VCN) are studied in this paper using RRKM, Kinetic Monte Carlo (KMC), and quasi-classical trajectory (QCT) calculations. A new HCN elimination pathway proves to be very competitive with the traditional 3-center and 4-center mechanisms, particularly at low excitation energies. However, low excitation energies have never been experimental...

The HCN emission features near 3 μm recently detected by Geballe et al. (2003, Astrophys. J. 583, L39) are analyzed with a model for fluorescence of sunlight in the ν3 band of HCN. The emission spectrum is consistent with current knowledge of the atmospheric temperature profile and the HCN distribution inferred from millimeter-wave observations. The spectrum is insensitive to the abundance of H...

Purpose Phosphene perception is a characteristic side effect of heart rate-reducing medication that acts on hyperpolarization-activated cyclic nucleotide-gated (HCN) ion channels. It is hypothesized that these phosphenes are caused by blocking HCN channels in photoreceptors and neurons of the retina, yet the underlying changes in visual signal processing in the retina caused by the HCN channel ...

Spinal cord injury (SCI) leads to bereft voluntary control of bladder, but the possible role of spontaneous excited system in bladder of SCI patients is poorly understood. Hyper-polarization-activated cyclic nucleotide-gated (HCN) channels are deemed to regulate the spontaneous contraction of bladder, our study explored the functional role of HCN channels in SCI induced neurogenic bladder. Sixt...

Hormone and neurotransmitter release from vesicles is mediated by regulated exocytosis, where an aqueous channel-like structure, termed a fusion pore, is formed. It was recently shown that second messenger cAMP modulates the fusion pore, but the detailed mechanisms remain elusive. In this study, we asked whether the hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which are a...

Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels comprise a family of cation channels activated by hyperpolarized membrane potentials and stimulated by intracellular cyclic nucleotides. The four members of this family, HCN1-4, show distinct biophysical properties which are most evident in the kinetics of activation and deactivation, the sensitivity towards cyclic nucleotides a...

The hyperpolarization-activated current (I(h)) contributes to intrinsic properties and network responses of neurons. Its biophysical properties depend on the expression profiles of the underlying hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels and the presence of cyclic AMP (cAMP) that potently and differentially modulates I(h) conducted by HCN1, HCN2 and/or HCN4. Here, we s...

Human poisoning caused by ingestion of unripe fruit of Passiflora ade/lOpoda is he re reported, apparently for the first time. HCN is pl'Ocluced in the pericarp and aril of tbe unripe fruit, as well as in tbe primary stem, petiole, br;¡cts and stipules but not in tendrils. HCN yield has been reported previously in Passifloraceae only from vegetative parts. The pericarp and arils of complctely r...

The effects of acidic pH on several voltage-dependent ion channels, such as voltage-dependent K+ and Ca2+ channels, and hyperpolarization-gated and cyclic nucleotide-activated cation (HCN) channels, were examined using a whole-cell patch clamp technique on mechanically isolated rat mesencephalic trigeminal nucleus neurons. The application of a pH 6.5 solution had no effect on the peak amplitude...