[Contraction of the isolated stomach of the rat as a result of stimulation of postganglionic fibers in the presence of 4-methylesculetol]. / Contrazione dello stomaco isolato di ratto per stimolazione di fibre post-gangliari, in presenza di 4-metilesculetolo.

It is known that the bioflavonoids as the Ca++ have an enhancing effect on the transmitter release in different cholinergic nerve-endings. For this reason, it is seemed interesting to study the influence of the separately tested 4-methylesculetin or associated with the ascorbic acid and comparatively the Ca++ concentration increase on the isolated rat stomach response by electrical transmural stimulation achieved in presence or absence of hexamethonium. Both the 4-methylesculetin and the ascorbic acid have always increased the response of the preparation submitted to electrical transmural stimulation. The 4-methylesculetin effect resulted particularly strong if the substance was employed with the ascorbic acid. The enhancing effect of the 4-methylesculetin, obtained with or without the ascorbic acid, is resulted comparatively lesser in presence of hexamethonium. On the basis of the evident analogy between the 4-methylesculetin effects and the ones determined by the increased Ca++ concentration, it can be supposed that the bioflavonoid facilitates the transmitter release in the pre- and postganglionic nerve-endings. The results here reported, confirm other previous observations accomplished on different cholinergic nerve-endings and could substain the hypothesis according to which the 4-methylesculetin increase the Ca++ transport through the biological membranes.

Comparative study of mechanical responses of hepatic arteries strips to adrenalin in presence of pyridoxine and pyridoxal-5'-phosphate.

Since it is known that PLP inhibits "in vitro" the COMT much more than pyridoxine; the influence of pyridoxine to the response of hepatic arteries isolated to AD has been compared to the influence of PLP to the same arteries. As for as the increase in percent is concerned, the result is that PLP gives rise to a greater answer to AD than pyridoxine. Such effects lacked when pyrogallol, a powerful COMT inhibitor, was present. Taking such results as a basis, it has been concluded that the mechanism of action of pyridoxine and of PLP was metabolic and that it was based on the COMT inhibition, even for the hepatic arteries. It was been also deduced that the higher efficiency of PLP compared to the pyridoxine's was due to its greater capacity to inhibit the COMT.

[Changes in acetylcholine contractions induced by carnitine in coronary vessels isolated "in vitro"]. / Modificazioni della contrazione da acetilcolina indotte dalla carnitina su vasi coronarici isolati "in vitro".

As suggested by literature about the carnitine's choline-mimetic effects, it has been studied the influence of this substance on the response to Ach of the isolated coronary arteries. It has been seen that Ach has often induced the contraction of the preparation that was preceded or abolished by atropine or prifinium bromide, or reduced by fendiline and verapamil. It resulted also that carnitine has always increased the entity of the contraction of the preparation treated with Ach and that the raising was abolished by fendiline or verapamil. Taking such results and suggestions from the literature as a basis, it has been concluded that the carnitine increased the response of the preparation to Ach, sensitizing muscarinic receptors which cause the entry of Ca++ throught the cell membrane.

[Effect of a bioflavinoid (4-methylesculetin) on the response of calf hepatic arteries to serotonin in the presence of indomethacin]. / Influenza di un bioflavonoide (4-metilesculetolo) sulle risposte di arterie epatiche di vitello alla serotonina in presenza di indometacina.

The aim of this work is to study the mechanism by which 4-methylsculetin (4-Me) inhibits the serotonin induced contraction in smooth muscle. The effect of 4-Me, alone or associated with ascorbic acid, on basal tone and serotonin induced contraction of isolated hepatic artery strips have been studied. Experiments have been carried out in the presence of indomethacin (IN), specific inhibitor of prostaglandin-synthetase. IN suppressed the depressive effect of 4-Me on the serotonin dependent contraction. Therefore, it seems reasonable to conclude that the 4-Me influence could be mediated by prostaglandins release smooth muscle.

[Effect of a flavinoid (4-methylesculetin) on the response of isolated calf coronary arteries to histamine in the presence of indomethacin]. / Influenza di un flavonoide (4-metilesculetolo) sulla risposta di arterie coronarie di vitello isolate all'istamina in presenza di indometacina.

The aim of this work is to study the mechanism by which 4-methylesculetin (4-Me) cause the relaxation or inhibit the histamine induced contraction in the smooth muscle. The effect of 4-Me, alone or associated with ascorbic-acid, on basal tone and histamine induced contraction of isolated coronary strips have been studied. Experiments have been carried out in the presence of indomethacin (IN), specific inhibitor of prostaglandin synthetase. IN-decreased, but did not abolished, the 4-Me induced relaxation and reduced or suppressed the depressive effect of 4-Me on the histamine dependent contraction. Therefore, it seems reasonable to conclude that the 4-Me influence could be mediated by prostaglandins release in the smooth muscle.

[Response of isolated coronary artery segments to serotonin in the presence of a flavinoid, indomethacin and acetylsalicylate]. / Risposte di segmenti di arterie coronarie isolate alla serotonina in presenza di un flavonoide, di indometacina e di acetilsalicilato.

The aim of this work is to study the mechanism by which 4-metilesculetin (4-Me) cause the relaxation or inhibit the serotonin induced contraction in the smooth muscle. The effect of 4-Me, alone or associated with ascorbic-acid, on basal tone and serotonin induced contraction of isolated coronary strips have been studied. Experiments have been carried out in the presence of indomethacin (IN), specific inhibitor of prostaglandin synthetase. IN-decreased, but did not abolished, the 4-Me induced relaxation and reduced or suppressed the depressive effect of 4-Me on the serotonin dependent contraction. Therefore, it seems reasonable to conclude that the 4-Me influence could be mediated by prostaglandins release in the smooth muscle.

[Responses of isolated hepatic artery segments to barium in the presence of a flavonoid (4-methylesculetin), indomethacin and acetylsalicylate]. / Risposte di segmenti di arteria epatica isolata al bario in presenza di un flavonoide (4-metilesculetolo) ed indometacina ed acetil-salicilato.

The aim of this work is to study the mechanism by which 4-methylesculetin (4-Me) inhibits the Ba++ induced contraction in smooth muscle. The effect of 4-Me, alone or associated with ascorbic acid, on basal tone and Ba++ induced contraction of isolated hepatic artery strips have been studied. Experiments have been carried out in the presence of lysine acetylsalicylate (LAS) and indomethacin (IN), specific inhibitors of prostaglandin-synthetase. Both LAS and IN suppressed the depressive effect of 4-Me on the Ba++ dependent contraction. Therefore, it seems reasonable to conclude that the 4-Me influence could be mediated by prostaglandins release smooth muscle.

[Ca++ dependence of the contraction of coronary artery segments in response to norepinephrine after beta-adrenergic blockade]. / Ca++-dipendenza della contrazione di segmenti di arteria coronaria in rispo sta alla noradrenalina dopo blocco beta-adrenergico.

The effect of external calcium concentration on the NE-induced contraction after beta-adrenergic blocking was studied in vitro. It resulted that the effect of NE was enhanced by increase, or reduced by decrease of calcium concentration. NE-induced contraction was not abolished when the bathing fluid was Ca++-free. The disappearance of the NE effect was only obtained in preparations treated with EDTA and perfused with Ca++-free Ringer-Locke solution. It is concluded that NE induced contraction after beta-adrenergic blocking is Ca++-dependent and on the tissue bound Ca++.

[Influence of 4-methylesculetol on the response of segments of isolated coronary arteries to adrenaline, in presence of pyrogallol]. / Influenza del 4-metilesculetolo sulle risposte di segmenti di arterie coronarie isolate all'adrenalina, in presenza di pirogallolo.

The adrenaline (AD) induced relaxation in the smooth muscle is increased by bioflavonoids, possibly via cathecol-0-methyltransferase (COMT) inhibition. In order to test this hypothesis, we studied the influence of 4-methylesculetin (4-Me), alone or associated with ascorbic acid, on the response of isolated coronary strips to AD, in the presence of pyrogallol. Both 4-Me being enhanced by the addition of ascorbic acid. The effects were reduced or abolished in the presence off pyrogallol, a well known COMT inhibitor. It is concluded that 4-Me inhibits COMT, as other bioflavonoids.

[Effect of prostaglandin-synthetase inhibitors on responses of segments of coronary arteries to 4-methylesculetol and/or to angiotensin II]. / Effetto di inibitori della PG-sintetasi sulle risposte di segmenti di arterie coronarie al 4-metilesculetolo e/o all'angiotensina II.

The aim of this work is to study the mechanism by which 4-methylesculetin (4-Me) causes the relaxation or inhibits the angiotensin-2 (ATN2) induced contraction in the smooth muscle. The effect of 4-Me, alone or associated with ascorbic acid, on basal tone and ATN2 induced contraction of isolated coronary strips have been studied. Experiments have been carried out in the presence of lysine acetylsalicylate (LAS) and indomethacin (IN), specific inhibitors of prostaglandin-synthetase. Both LAS and IN decreased, but did not abolish, the 4-Me induced relaxation and suppressed the depressive effect of 4-Me on the ATN2 dependent contraction. Therefore, it seems reasonable to conclude that the 4-Me influence could be mediated by prostaglandins release in the smooth muscle.

[Influence of bioflavonoid (4-methylesculetin) on the reaction of isolated calf hepatic artery to serotonin]. / Influenza di un bioflavonoide (4-metilesculetolo) sulle risposte di arterie epatiche isolate di vitello alla serotonina.

The effect of 4-metilesculetin on strips of calf hepatic arteries was investigated. 4-metilesculetin antagonizes the contraction induced by 5-HT probably through activation of the synthesis of vasodilator prostaglandins.

[Influence of desoxycorticosterone on the response of calf coronary artery strips to adrenaline]. / Influenza del desossicorticosterone sulle risposte di segmenti di arteria coronaria isolata all'adrenalina.

The effect of desoxycorticosterone on the adrenaline-induced relaxation of coronary arteries was studied "in vitro". It resulted that the effect of adrenaline was enhanced by desoxycorticosterone. It is concluded that desoxycorticosterone potentiates the effects of adrenaline by inhibiting its inactivation by Catechol-O-methyltransferase.

[Influence of 6-methylprednisolone on responses of isolated coronary arteries to adrenaline]. / Influenza del 6-metil prednisolone sulle risposte di arterie coronarie isolate all'adrenalina.

The effect of 6-Methylprednisolone on the adrenaline-induced relaxation was studied in vitro. Relaxation of response to adrenaline increased by 6-Methylprednisolone. We suggest that the 6-Methylprednisolone influence influence depends on inhibition of Catecol-O-methyl transferase (COMT).

[Influence of dexamethasone on the responses of isolated coronary arteries to adrenaline]. / Influenza del desametazone sulle risposte di arterie coronarie isolate all'adrenalina.

The effect of Dexamethasone on the adrenaline-induced relaxation was studied in vitro. Relaxation of response to adrenaline increased by Dexamethasone. We suggest that the Dexamethasone influence depends on inhibition of Catecol-O-methyl transferase (COMT).