Biomedical subjects

L Cartas-Heredia

Publications and source records attributed to L Cartas-Heredia.

4 recordsLinked to original sources

PubMed1997

Vasoconstrictor effect of Cissus sicyoides on guinea-pig aortic rings.

1. The effect of the aqueous extract of Cissus sicyoides (CS) on isolated guinea pig aortic rings was studied. CS contracts the smooth muscle of the aorta in a dose-response relation. 2. The extract of CS increases the norepinephrine contraction in normal calcium and in solutions without calcium. 3. Lanthanum inhibits the contraction induced by CS. 4. The vasoconstrictor effect of CS was increased in solutions without calcium or with low calcium, which is an inverse calcium-dependent contraction. 5. Prolonged exposure to calcium-free solution did not abolish CS contraction. These contractions can be elicited repeatedly even after 6 hr of continuous exposure to calcium-free solutions. 6. Caffeine reduces contractile response induced by CS in normal calcium, as well as in solutions without calcium. 7. Our results support the idea that the aqueous extract of CS acts at the membrane level, increasing the calcium entry through the membrane as well as acting on the internal calcium deposits, possibly on the sarcoplasmic reticulum.

Adrenergic alpha-Agonists↗

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↗

PubMed1988

Chronic bladder catheterization in the rat.

A technique for the implantation of a permanent polyethylene catheter into the bladder is described. The procedure permits collecting the subject's urine in arbitrary periods of time during at least four to six weeks.

Animals↗

PubMedDate not supplied

Oestrogenic influences on the electrical activity of the olfactory pathway.

The influence of the oestrogenic hormones over the spontaneous and induced activity of the olfactory pathway was studied in normal female cats. Electrodes were placed chronically or acutely in the olfactory bulb (OB), olfactory tubercle (OT) and in the prepyriform cortex (PPC). Oestrogenic hormones were applied locally in the posterior hypothalamic region. Recordings were made during the two different phases of the oestral cycle. In addition, another group of castrated animals was studied. The oestral phase was induced in these cats by the subcutaneous administration of 17-beta-oestradiol. Results indicate that the pattern of the electroencephalographic spontaneous activity as well as the response induced by hypothalamic stimulation changed. The number of the bursts for each 10 sec trace was higher in oestrus than in anoestrus for all the structures studied. The duration of each burst also changed, being shorter in oestrus than in anoestrus cats. The threshold for significant bursting in the olfactory structures following hypothalamic stimulation was lower in oestrus than in anoestrus. The evoked potentials recorded in the same three olfactory structures by hypothalamic stimulation exhibited changes in correlation with the hormonal administration. In all the structures studied the amplitude of the different components of the evoked potentials increased immediately after the hormones were administered. However, the most dramatic increase was observed in the olfactory tubercle. In order to further investigate these changes in acute preparations, a study evaluating the excitability changes was conducted. Applied pulse pairs, with different interpulse intervals between 200 to 1000 msec, were delivered in the hypothalamus before and after 200 micrograms of the hormone were administered into the posterior hypothalamus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗