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Biomedical subjects

E Gijon

Publications and source records attributed to E Gijon.

10 recordsLinked to original sources
PubMed1995

Actions of perezone on rat smooth muscle.

1. Perezone (PZN) on the in vitro intestinal smooth muscle of the rat relaxes the basal tonus of the smooth muscle, interrupts spontaneous activity and also blocks the contractile response induced by ACh, K+, and Ba2+; these actions are dose dependent. 2. Although in presence of small doses of PZN, the isometric contractile response to ACh was increased. 3. In calcium free intestinal smooth muscle preparation, the addition of PZN in low dose before Ca2+ increased the contractile effect of added calcium to the bath, but in presence of high doses of PZN the response to calcium was depressed. 4. PZN in calcium free preparations antagonized the contraction caused by adding barium. 5. These findings suggested that with small doses of PZN more availability of intracellular calcium free exist and/or an increase in excitability and/or an inhibition of AChase could coexist. 6. The responses of the intestine to high doses of PZN were possibly in part by blocking calcium entry. 7. The smooth muscle responses to PZN suggest that it has a membranal effect and/or an action on the internal calcium stores possibly increasing the intracellular calcium concentration. It is likely to be the expression of an increase in the intracellular calcium concentration above the levels normally reached that would be responsible for uncoupling of the smooth muscle, which would occur if the [Ca2+]i rises excessively.

Acetylcholine↗
PubMed1992

Effect of the length of degenerating phrenic nerve fibres on the anaphylactic contraction of the diaphragm.

1. The effect of denervation on the anaphylactic contraction of the diaphragm from actively sensitized guinea pig has been studied. 2. The section of the phrenic nerve took place at cervical and thoracic levels. The sensitization of the animal took place several days before sectioning, simultaneously with denervation and after denervation. 3. The anaphylactic contractions were observed from the fourth day after thoracic denervation, and from the sixth day when denervation was in the cervical region. 4. The hypersensitivity to ACh in the denervated diaphragmatic muscle was present 24 hr after sectioning the phrenic nerve and reached its maximum 3-4 days after. 5. These results support the idea that denervation caused some changes in the membrane of the skeletal muscle fibres to allow the fixation of antibodies. These denervation changes are dependent on the length of the peripheral nerve left to degenerate. Anaphylactic contractions appeared earlier in those animals where phrenic nerve sections were closer to the diaphragmatic muscle.

Acetylcholine↗
PubMed1988

Ca2+-agonistic effects of diazepam, a benzodiazepine 1-4 derivative, on isolated mouse and guinea pig left atria.

In normal Krebs solution, diazepam (1.75X10(-4) M) increased the action potential duration in a reversible form and caused a positive inotropic effect on mouse auricular muscle (4). 2.) Further studies on diazepam action on electrical and mechanical activity of left auricular muscle from mouse and guinea pig, in preparations electrically driven, showed that diazepam induces an increase in action potential duration measured at 20% repolarization, a decrease in the rate of spike depolarization, and modifies the conduction velocity of the action potential. 3.) Diazepam produced in preparation with spontaneous activity, positive chronotropic and inotropic effects, and positive inotropic effect in electrically driven preparations. 4.) The change in action potential duration induced by diazepam on mouse preparations was higher than on guinea pig preparations, ca.X3. 5.) These findings support that diazepam action may be due to an increase in the inward calcium current and a reduction in the inward sodium current.

Animals↗
PubMed1988

Anaphylactic reaction in smooth muscle from the duck.

1. To know if the absence of desensitization in the chicken is characteristic of avian tissues, we studied the anaphylactic reaction in the duck. The contractions elicited in pieces of small intestine of actively immunized ducks upon exposure to the specific antigen, or Schultz-Dale reaction, were compared to similar responses of sensitized chicken and guinea pig intestine. 2. The smooth muscle from chicken actively sensitized contracts, when it is exposed in vitro to the specific antigen. Maximal tension, developed during anaphylactic reaction, is kept until the preparation is washed. New exposure of the muscle to the antigen causes it to develop tension again. This means that exposure to the antigen does not desensitize chicken intestine. 3. Intestinal smooth muscle from sensitized duck developed tension when the specific antigen was added to the bath; the tension was transitory and soon reached the basal line, even before washing the antigen. Contrary to the observations in the chicken smooth muscle, a second antigen dose failed to elicit a contraction of the duck intestine. Duck smooth muscle behaved like mammalian tissue. Exposure to the antigen desensitized duck intestine. 4. On multiple sensitized duck, the order of addition of antigens and their desensitization, did not alter the anaphylactic response to each antigen. 5. These observations are discussed in terms of the known properties of duck antibodies.

Acetylcholine↗