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F Alonso-deFlorida

Publications and source records attributed to F Alonso-deFlorida.

8 recordsLinked to original sources
PubMed1992

Changes in mast-cell distribution in skeletal muscle after denervation.

Motor nerves are known to govern the structure of skeletal muscle. In the normal guinea pig diaphragmatic muscle, we found that mast cells were predominantly located in the central tendon. Following denervation, these cells became more numerous in the muscle itself than in the tendon. Therefore, nervous trophic influences are exerted on other tissue elements besides those which sustain transmission and contraction. Ascertaining mast-cell distribution in biopsies may help to elucidate denervation effects in motor neuron disease.

Animals↗
PubMed1991

Modulated long-term potentiation in the cat superior cervical ganglion in vivo.

In the sympathetic ganglion a high frequency conditioning train produces a post-train potentiation (PTrP) which decays with a temporal course that can be described by two components: an early faster component known as post-tetanic potentiation (PTP), and a long-lasting one which is known as long-term potentiation (LTP). The magnitude of PTP and LTP is thought to be a function of the subliminal fringe size. Moreover, under full activation of ganglion cells LTP does not appear due to the saturation conditions. LTP emerges only when the subliminal fringe is increased, and to achieve this, a low-level tetanization must be performed. However, another possibility, explored in this paper, is that in addition to the desaturation effect of the low-level conditions of tetanization, a different mechanism, responsible for the LTP appearance, may be introduced by these low-level conditions of tetanization. This possibility implies a variable LTP according to the input conditions; accordingly, the shape of LTP was compared in 4 experimental conditions in which the input to the ganglion cells was different; (1) supramaximal activation of the intact cervical sympathetic trunk (CST), (SPM); (2) submaximal activation of the intact CST, (SBM); (3) supramaximal activation of the partially transected CST, (TRN): and (4) supramaximal activation of the intact CST under partial nicotinic block with hexamethonium. (BLK). Even when PTrP was evoked with the same subliminal fringe obtained under the 3 low-level conditions of tetanization, the degree of potentiation and the proportion of PTP and LTP were different. After either SPM or SBM conditions LTP was negligible, though PTP developed to a certain degree.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

A synaptic model for the kindling effect.

In this work we present a model of the kindling effect based on the Hopf bifurcation for a system of ordinary differential equations. The model shows how quantitative changes in the physiological parameters at the microscopic, synaptic scale, produce the afterdischarge which is a macroscopic effect at the neuronal network scale. The presynaptic mechanisms are based on the vesicular hypothesis, or more generally on the quantal theory of synaptic transmission. The postsynaptic processes rely on Granit's law. This model gives a consistent framework which organizes and explains several experimental observations.

Animals↗
PubMed1980

Isometric responses in the denervated diaphragmatic muscle of the guinea pig elicited by antigen and histamine.

Denervated diaphragmatic muscle strips from the guinea pig responded in vitro to varying concentrations of histamine with isometric contractions. Dose-response curves from strips taken from several areas of the muscle (ventral, V; dorsal, D; lateral, L) had slopes which were related in the following manner: D greater than V greater than L. Nevertheless, when the curves were normalized with respect to a dose which produced maximal tension, the slopes were similar and could be superimposed. Preparations taken from animals allergized to either bovine serum albumin or ferritin responded to the antigen with isometric contractions which also differed according to the original location of the strip in the muscle (D greater than V greater than L), but were similar when normalized as above. The results obtained from the normalized curves reflect a uniform sensitivity to histamine and antigen throughout the muscle. The variations in tension developed in the different strips probably are related to their contractile mass. The isometric recordings also revealed the development of spontaneous muscular contractions, as well as the presence of response latencies to both histamine and antigen, but not to acetylcholine.

Animals↗
PubMed1977

The in vitro effects of calcium and potassium in resensitization of tracheal smooth muscles of the allergized guinea pig.

Tracheal smooth muscle obtained from allergized guinea pigs gives rise in vitro to two-phase cycles of responsiveness to antigen administration desensitization produced immediately after a conditioning antigen dose, followed by resensitization within 4 h. As in the case of resensitization to a drug, resensitization to an antigen is a Ca++- and K+-dependent phenomenon. A comprehensive receptor model of the chemical excitatory action of antigen in cells is consistent with a Ca++-dependent resensitization phenomenon in the allergized systems. On the other hand, the results bear weight against both a 'pharmacological mediator-depletion theory' and an 'antibody saturation-desaturation theory', which have been invoked to explain desensitization and resensitization to antigen in allergized systems.

Animals↗
PubMedDate not supplied

Posttetanic potentiation in decentralized and nondecentralized superior cervical ganglia of the cat.

The present investigation was aimed to answer the following elementary, though important question concerning the sympathetic ganglion: Do the decentralized preganglionic terminals retain their full capacity to develop posttetanic potentiation (PTP) before substantial Wallerian degeneration takes place? Experiments were performed on the cat superior cervical ganglion in situ, and they followed a factorial design. The factors were: tetanization (supramaximal pulses, 0.2 ms, 24 Hz, 30 s), acute decentralization, and moderate hexamethonium blockade (5 mg/kg). Two levels were dealt with, namely, the indicated maneuvers were either performed or not performed. PTP was was measured in the S2 wave and the following variables were studied: decay constant, area under the curve and delay to summit occurrence. The analysis of variance showed that decentralization did not affect the development of PTP. Therefore, the nondegenerated terminals are fully capable of sustaining PTP, without the aid of the preganglionic cell bodies.

Action Potentials↗
PubMedDate not supplied

Antigen-induced antigen endocytosis in primitive reticular cells of connective tissue of innervated and denervated skeletal muscle from the allergized guinea pig.

Electron microscope studies demonstrated that soluble proteins (ferritin and horseradish peroxidase) administered in vitro to strips of guinea pig diaphragmatic muscle under physiological conditions were internalized by vesicles of primitive reticular cells (PRCs) found in the connective tissue. This endocytosis effect was enhanced when the muscle preparations were obtained from animals actively allergized to the protein. Denervation increased the occurrence of peroxidase-positive vesicles in the peroxidase-antiperoxidase system. These results suggest that the antigen-antibody interaction induces endocytosis directed to the specific antigen.

Animals↗