Infrared pumping and its effect on the excitation of HCN molecules can be important when using rotational lines of HCN to probe dense molecular gas in galaxy nuclei. We report the first extragalactic detection of (sub)millimeter rotational lines of vibrationally excited HCN, in the dust-enshrouded nucleus of the luminous infrared galaxy NGC 4418. We estimate the excitation temperature of Tvib ≈...

Hyperpolarization-activated, cyclic-nucleotide-gated (HCN) channels mediate the depolarizing cation current (termed I(h) or I(f)) that initiates spontaneous rhythmic activity in heart and brain. This function critically depends on the reliable opening of HCN channels in the subthreshold voltage-range. Here we show that activation of HCN channels at physiologically relevant voltages requires int...

We have carried out a survey of C2H and HCN in a wide sample of evolved stars using the 30-m IRAM telescope. Significant variations of the C2H abundance are found between the observed stars. Low C2H abundances, X(C2H)<10−5, are observed in S-stars, and detached envelopes. In massive C-rich stars (Ṁ > 2 10−6 M yr−1) the C2H abundance seems to be correlated with the expansion velocity. Thus, the ...

Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are expressed as four different isoforms (HCN1-4) in the heart and in the central and peripheral nervous systems. HCN channels are activated by membrane hyperpolarization at voltages close to resting membrane potentials and carry the hyperpolarization-activated current, dubbed If (funny current) in heart and Ih in neurons. HCN c...

We report systematic HCN(1-0) observations (and CO observations) of a sample of 53 infrared (IR) and/or CO bright and/or luminous galaxies, including 7 ultraluminous infrared galaxies, nearly 20 luminous infrared galaxies, and more than a dozen nearest normal spiral galaxies. This is the largest and most sensitive HCN survey of galaxies to date. All galaxies observed so far follow the tight cor...

Rovibronic energy levels and properties of the Br(2P)-HCN complex were obtained from three-dimensional calculations, with HCN kept linear and the CN bond frozen. All diabatic states that correlate to the 2P3/2 and 2P1/2 states of the Br atom were included and spin-orbit coupling was taken into account. The 3 x 3 matrix of diabatic potential surfaces was taken from the preceding paper (paper 1)....

[1] We construct global atmospheric budgets of HCN and CH3CN through a threedimensional (3-D) model simulation of the HCN-CH3CN-CO system constrained and evaluated with aircraft observations from the Transport and Chemical Evolution Over the Pacific (TRACE-P) mission over the NW Pacific in February–April 2001. Observed background vertical gradients of HCN and CH3CN imply a dominant ocean sink f...

We report systematic HCN J=1-0 (and CO) observations of a sample of 53 infrared (IR) and/or CO-bright and/or luminous galaxies, including seven ultraluminous infrared galaxies, nearly 20 luminous infrared galaxies, and more than a dozen of the nearest normal spiral galaxies. This is the largest and most sensitive HCN survey of galaxies to date. All galaxies observed so far follow the tight corr...

Vemana S, Pandey S, Larsson HP. Intracellular Mg is a voltage-dependent pore blocker of HCN channels. Am J Physiol Cell Physiol 295: C557–C565, 2008. First published June 25, 2008; doi:10.1152/ajpcell.00154.2008.—Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are activated by membrane hyperpolarization that creates time-dependent, inward rectifying currents, gated by the mov...