Effects of internal Sr2+ on the activity of large-conductance Ca2+-activated K+ channels were studied in inside-out membrane patches from goldfish saccular hair cells. Sr2+ was approximately one-fourth as potent as Ca2+ in activating these channels. Although the Hill coefficient for Sr2+ was smaller than that for Ca2+, maximum open-state probability, voltage dependence, steady state gating kine...

We derive structural and binding energy trends for twenty amino acids, their dipeptides, and their interactions with the divalent cations Ca2+, Ba2+, Sr2+, Cd2+, Pb2+, and Hg2+. The underlying data set consists of more than 45,000 first-principles predicted conformers with relative energies up to ~4 eV (~400 kJ/mol). We show that only very few distinct backbone structures of isolated amino acid...

Acetylcholine-evoked currents mediated by activation of nicotinic receptors in rat parasympathetic neurons were examined using whole-cell voltage clamp. The relative permeability of the neuronal nicotinic acetylcholine (nACh) receptor channel to monovalent and divalent inorganic and organic cations was determined from reversal potential measurements. The channel exhibited weak selectivity among...

Ca2+ currents (ICa) were recorded from the neurosecretory terminals of the crab X-organ-sinus gland under voltage-clamp conditions. ICa was detectable at command potentials above -40mV, with maximum currents at approximately +20mV. No differences were observed between current-voltage (I/V) relationships from holding potentials of -50 or -90mV, indicating that there were no low-voltage-activated...

In this study, a series of interaction coefficients of the Brønsted-Guggenheim-Scatchard specific interaction theory (SIT) have been estimated up to 200 degrees C and 400 bars. The interaction coefficients involving Cl- estimated include epsilon(H+, Cl-), epsilon(Na+, Cl-), epsilon(Ag+, Cl-), epsilon(Na+, AgCl2 -), epsilon(Mg2+, Cl-), epsilon(Ca2+, Cl-), epsilon(Sr2+, Cl-), epsilon(Ba2+, Cl-), ...

Inactivation of Ca channels was examined in crab muscle fibres using the voltage-clamp method. A satisfactory suppression of outward currents was attempted by the use of K+ blocking agents: TEA, 4AP and Cs ions instead of K+ ions applied extracellularly. The inactivation of Ca current appeared as a bi-exponential process. The faster component had a mean value of the time constant of 50 ms while...

A Na+/Ca2+ exchange mechanism has been recently described in human neutrophils that constitutes the principal pathway for Ca2+ influx into resting cells. The potential role of this system in regulating the respiratory burst in response to activation by the chemotactic tripeptide N-formyl-methionyl-leucyl-phenylalanine was explored. In the presence of 1 mM Ca2+, a variety of di- and trivalent ca...

1. In order to discover whether the changes in reactivity are related to the primary cause of hypertension in spontaneously hypertensive rats (SHR) or are just an adaptation induced by the high arterial blood pressure we tested the contractile response of a visceral smooth muscle from such rats. 2. Longitudinal strips of the fundus from 20 week old male and female SHR and Wistar normotensive (...