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Biomedical subjects

J Marin

Publications and source records attributed to J Marin.

At least 73 records · Page 4Linked to original sources
PubMed1986

Effect of some vasodilators on cat femoral arteries.

Adenosine, cyclic-AMP (cAMP), papaverine and 1-methyl-3-isobutylxanthine (MIX) evoked dose-dependent vasodilatation in cat femoral arteries precontracted with 75 mM K+. The vasodilator response induced at maximal concentration used was: papaverine greater than MIX greater than adenosine = cAMP. With regard to the potency of relaxant effects (IC10) the order was MIX = cAMP = papaverine greater than adenosine. The dilatation elicited by papaverine, adenosine and cAMP was increased by MIX. Preincubation with adenosine enhanced the relaxation induced by MIX and reduced that produced by cAMP. These results indicate that the effects of adenosine and cAMP seem not to be mediated by specific surface receptors but by a cAMP-dependent mechanism. The interference between adenosine and cAMP could be due to competition for a similar site and/or mechanism.

1-Methyl-3-isobutylxanthine↗
PubMed1985

The effects of BAY-K-8644 on the contraction of cat middle cerebral and femoral arteries.

The effects of BAY-K-8644 on the reactivity of cylindrical segments of cat middle cerebral and femoral arteries were studied. BAY-K-8644 induced dose-dependent contractile responses in cerebral arteries up to 10(-6) M; higher concentrations tended to cause relaxation of the segments. The dihydropyridine elicited contractions in femoral arteries only when these vessels were previously exposed to 15 mM K+. Nifedipine (3 X 10(-7) M) produced a parallel shift to the right of the dose-response curve to BAY-K-8644, whereas 5 X 10(-6)M verapamil markedly reduced the responses evoked by all concentrations of this drug. The removal of Ca2+ from the medium abolished the response evoked by the Ca2+-channel activator at 10(-7) M in both kinds of arteries. Under these conditions Ca2+ addition induced vasoconstriction, which was blocked by nifedipine (3 X 10(-7) M). Preincubation of femoral arteries with 10(-7) M BAY-K-8644 potentiated the effects evoked by 25, 50, 75 and 125 mM K+, but did not modify those produced by 10(-5) M noradrenaline. Nifedipine (10(-7) M and 3 X 10(-7) M) blocked the potentiation caused by this drug in a dose-dependent manner. Both the increase of the response elicited by BAY-K-8644 and the inhibitory effects of nifedipine were greater at 25 mM K+ than at 125 mM. These results suggest that BAY-K-8644 facilitates Ca2+ influx into smooth muscle through Ca2+ channels that are possibly voltage sensitive and the voltage independence of the drug-induced contractions in cerebral arteries.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1985

Study of vasodilator effects of papaverine, adenosine and related drugs in isolated cat cerebral arteries.

Papaverine, 1-methyl-3-isobutylxanthine (MIX), adenosine, cyclic-AMP (cAMP),dibutyryl-cAMP (db-cAMP) evoked concentration-dependent vasodilation in cat middle cerebral arteries precontracted with K+. The order of maximal vasodilator responses was: papaverine greater than MIX greater than adenosine = cAMP greater than or equal to db-cAMP, and with regard to their potency (ED50) was: db-cAMP greater than cAMP greater than papaverine = MIX greater than adenosine. The relaxations induced by papaverine, adenosine and cAMP were reduced by MIX. Preincubation with adenosine increased the vasodilation evoked by MIX. It also transformed the relaxation caused by cAMP in contraction. These results suggest that adenosine and related compounds interact with specific purinoreceptors, as well as the existence of two antagonisms between: adenosine and cAMP, papaverine and MIX for the same site or mechanism of action.

1-Methyl-3-isobutylxanthine↗
PubMed1985

[Pneumocystis carinii in the bone marrow].

Pneumocystis carinii is observed in the bone marrow of two adults immuno-compromised; the initial diseases are on the one hand a Hodgkin's disease, on the other hand a malignant lymphoma for immunocytoma type, which necessitate heavy and invalidating treatments. A Pneumocystis carinii pneumonia with respiratory distress seems to have carrying away two patients death. Eventually pathogenic part of the parasite in the bone marrow localization.

Adult↗
PubMed1984

Physicians' attitudes toward breast self-examination: a pilot study.

Recent case control studies suggest that breast self-examination (BSE) is efficacious in the early clinical diagnosis of breast cancer. Population studies also indicate that adoption of this behavior depends largely on physicians. This pilot study was designed to determine whether physicians' attitudes on this subject could be obtained through a mail questionnaire. The results show that a self-administered mail questionnaire can be used successfully in physician studies. Although questionnaire length does affect response rates (78% one page, 69% four page, and 57% eight page), it does not affect either respondent characteristics or question response.

Attitude of Health Personnel↗
PubMed1983

Effects of verapamil and manganese on the vasoconstrictor responses to noradrenaline, serotonin and potassium in human and goat cerebral arteries.

The effects of verapamil and manganese (Mn2+) on the noradrenaline (NA), serotonin (5-HT) and potassium (K+)-induced contractions were studied in human and goat cerebral arteries. Verapamil and Mn2+ relaxed both kinds of cerebral vessels previously contracted with 10(-5) M NA, 10(-5) M 5-HT and 75 mM K+. The ID50 (50% inhibition of maximum contraction) was around 10(-7) M for the organic antagonist and 10(-3) M for the inorganic one. The ID50 for the Ca2+ antagonists in K+-induced contractions was smaller than that for NA and 5-HT-evoked contractions. Preincubation of segments with verapamil (10(-6) M) or Mn2+ (2 X 10(-3) or 5 X 10(-3) M) caused inhibition of the contractions evoked by the three agents that was greater in the case of K+. The inhibitory effects of verapamil were reversed by adding Ca2+ to the bath. The removal of Ca2+ from the extracellular medium reduced the contractions elicited by the three vasoconstrictor agents in both cerebral blood vessels. This reduction was greater for K+ than for the other two. These results indicate that both cerebral vessels are very susceptible to Ca2+ omission and to Ca2+ entry blockers such as verapamil and Mn2+, which could be of interest to treat cerebral vasospasm.

Animals↗
PubMed1981

Localization of adrenergic neurons in human and cat meninges.

In human and cat meninges the presence of adrenergic neurons was studied. The human meninges were obtained from 10 adult individuals 1-3 hours postmortem and the 6 cats meninges, one pretreated 7 days before the experiment with 5 mg of 6-OHDopamine intracisternally. In human and cat meninges, adrenergic granulations, located in fibers that form a reticulum around the arterial, arteriolar and small vein vessels were observed. These adrenergic fibers appeared forming a very dense reticulum in the adventitia of the small calibre arteries and in arterioles. In addition, in some vascular sectors, a considerable number of triangular or elongated cells, whose cytoplasm is full of adrenergic granulations can be observed isolated or in close vicinity to the adrenergic reticulum. In the meninges of the cat treated with 6-OH-Dopamine there was no adrenergic granulation. Furthermore, the radioenzymatic determination of noradrenaline content in 3 human meninges shows the existence of this amine. The number of cellular elements with adrenergic granulations is notable and permits one to suspect that this cellular system can play an important role in the autoregulation on the cerebral circulation together with the perivascular adrenergic reticulum.

Adrenergic Fibers↗
PubMed1981

Noradrenergic component in the vasoconstriction induced by 5-hydroxytryptamine in goat cerebral arteries.

5-Hydroxytryptamine (5-HT) elicited dose-dependent increases in tension in the middle cerebral artery of the goat, which were significantly antagonized by lysergic acid diethylamide (LSD, 10(-8) M) and methysergide (10(-7) M). In the presence of phentolamine (10(-6) M), the dose-response curve to 5-HT was shifted to the right, the pA2 value for this antagonism was 6.52. Pretreatment of goats with reserpine (0.02 mg kg-1 day-1 for three days) or removal of both superior cervical ganglia 15 days before the experiment brought about a significant decrease in the vasoconstriction induced by doses of 5-HT higher than 10(-7) M. The remaining contraction produced by 5-HT in arterial segments from reserpinized or gangliectomized goats was further reduced in the presence of LSD. In addition, high concentrations of 5-HT induced tritium release from goat pial arteries preloaded with (-)-[3H]noradrenaline, 2 X 10(-7) M) which was significantly decreased in vessels from gangliectomized or reserpinized goats. These results in goat cerebral arteries indicate that in the contraction evoked by 5-HT there are two components. The first appears with low concentrations (up to 10(-7) M) in which 5-HT acts directly on 5-HT receptors. The second occurs at high doses (greater than 10(-7) M) in which 5-HT also acts indirectly on alpha-adrenoceptors by release of noradrenaline from noradrenergic nerve endings.

Animals↗
PubMed1980

Influence of calcium on noradrenaline release evoked by 5-hydroxytrypamine and potassium from goat pial arteries.

The release of tritium (3H) evoked by tyramine, potassium (K+) and 5-hydroxytryptamine (5-HT) from goat pial arteries preloaded with [3H]noradrenaline (3H-NA) was studied. In normal Krebs-bicarbonate solution (KBS) all these agents caused a transient increase in radioactivity release over the basal spontaneous outflow. The pattern of release evoked by 5-HT was similar to that induced by tyramine with a slow onset and decline, but different from that induced by K+ which produced a rapid peak of 3H release followed by a quick fall. The removal of Ca2+ from the medium did not modify the efflux of radioactivity caused by tyramine, but the 3H efflux produced by K+ was markedly reduced. Nevertheless, in this Ca2+-free medium the 3H release evoked by 5-HT was partially, but significantly, decreased. These results indicate that K+ evokes NA release by a Ca/+-dependent process, probably of an exocytotic nature, while tyramine mediates NA release by means of a Ca2+-independent mechanism. However, 5-HT possesses a Ca2+-dependent and a tyramine-like component.

Animals↗
PubMed1979

Release of [3H]noradrenaline induced by 5-hydroxytryptamine from cat pial arteries.

Pial arteries of cats were used to analyse the effects of 5-hydroxytryptamine (5-HT) on the release of [3H]noradrenaline. To achieve this the vessels were preincubated with [3H]noradrenaline and the effect of different concentrations of 5-HT (10(-6), 10(-5), 10(-4) M) on the release of tritium was studied. 5-HT elicited release of radioactivity in a dose-dependent manner. Removal of both superior cervical sympathetic ganglia 15 days before the experiment of pretreatment of the animals with reserpine (3 mg kg-1, total dose) produced a significant decrease in the outflow of tritium induced by 5-HT. In these arteries, the amount of radioactivity retained at the end of the experiment was much diminished. Cocaine (10(-6) M) caused a significant decrease in the tritium efflux induced by 5-HT (1"0(-5) M). These results show that 5-HT has an indirect adrenergic effect in the pial arteries of the cat only at high doses of 5-HT, and confirm that sympathetic innervation of these vessels mainly comes from the superior cervical ganglia.

Animals↗