Ubaldo García

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1. The patterns of electrical activity and membrane characteristics of a population of neurosecretory-cell somata in the X-organ of the crayfish were investigated with microelectrodes and whole-cell, voltage-clamp techniques. Some neurons (56%) were silent but could be excited by intracellular current injection: other cells showed spontaneous tonic activity(More)
The effect of 5-hydroxytryptamine (5-HT) was tested in a population of X organ neurosecretory cells in the eyestalk of the crayfish Procambarus clarkii. Tests were conducted both in situ and on isolated neurones kept in culture. The application of 5-HT induced action potentials in silent cells. In spontaneously active neurones, 5-HT increased the firing(More)
The effects of 5-hydroxytryptamine (5-HT) were investigated in red pigment concentrating hormone (RPCH)-containing neurons isolated from the X-organ of the crayfish (Procambarus clarkii). Under current-clamp conditions and using the gramicidin-perforated-patch configuration, 5-HT elicited a prolonged hyperpolarization that suppressed neuronal firing(More)
Thapsigargin-sensitive sarco/endoplasmic reticulum Ca(2+) pumps (SERCAs) are involved in maintaining and replenishing agonist-sensitive internal stores. Although it has been assumed that release channels act independently of SERCA pumps, there are data suggesting the opposite. Our aim was to study the relationship between SERCA pumps and the release(More)
1. Intracellular and voltage-clamp recordings were obtained from a selected population of neurosecretory (ns) cells in the X organ of the crayfish isolated eyestalk. Pulses of gamma-aminobutyric acid (GABA) elicited depolarizing responses and bursts of action potentials in a dose-dependent manner. These effects were blocked by picrotoxin (50 microM) but not(More)
A novel crustacean toxin (Cn11) was isolated and characterized from the venom of the Mexican scorpion Centruroides noxius Hoffmann. It contains 63 amino acid residues and is stabilized by four disulphide bridges. It is lethal to crustaceans (Cambarellus montezumae), less toxic to insects (crickets) and non-toxic to mammals (mice) at the doses assayed. In(More)
1. The X organ-sinus gland system is a conglomerate of 150-200 neurosecretory cells in the eyestalk of crustaceans. It is the source of a host of peptide neurohormones which partake in the control of a wide range of physiological functions. Distinct families of X organ peptides have been chemically characterized: (a) two chromatophorotropic hormones of(More)
1. Intracellular and voltage-clamp recordings were obtained from a selected population of neuroscretory (ns) cells in the X organ of the crayfish isolated eyestalk. Pulses of γ-aminobutyric acid (GABA) elicited depolarizing responses and bursts of action potentials in a dose-dependent manner. These effects were blocked by picrotoxin (50 µM) but not by(More)
We have studied the effects of ryanodine and inhibition of the sarco/endoplasmic reticulum Ca(2+) ATPase (SERCA) with thapsigargin, on both [Ca(2+)](i) and the sarcoplasmic reticulum (SR) Ca(2+) level during caffeine-induced Ca(2+) release in single smooth muscle cells. Incubation with 10 microM ryanodine did not inhibit the first caffeine-induced(More)