Contractilidad "in vitro" de los vasos coriales de la placenta humana: efecto del peróxido de hidrógeno / \"In vitro\" contractility of chorionic vase of human placenta: hydrogen peroxide effect

Según metodología descripta en trabajos anteriores, se estudia la contractilidad "in vitro" de los vasos coriales de 30 placentas humanas normales, y el efecto provocado por el aumento del PO**2 en el medio perfusor a expensas de concentraciones de H**2 O**2 de 1.25, 2.5 y 5.0 mM. El H**2 O**2 provoca una respuesta contráctil monofásica; la intensidad de la contraccíon aumenta proporcionalmente a la concentración de H**2 O**2 (F = 8.9 p > 0,01). La indometacina y la aspirina a concentraciones de 2.5 micronM y 0.25 mM respectivamente, inhiben aquella respuesta

Spontaneous contractility of human placental vessels in vitro axipetal and isometric recording.

In vitro contractility of isolated cylindrical segments of chorial arteries and veins from 40 human term placentas was studied. Contractility was recorded by an isometrical and axipetal method. Spontaneous contractility was observed in 75% of the arteries and in 45% of veins. In both types of vessels, contractility was similar and characterized by development of tonic circumferential tension, between 100 and 200 mg/mm. Clonic activity consisting of rhythmic contractions with an average frequency between 0.7 and 0.9/min and an average intensity of 5--40 mg/min was superimposed. Vasoconstrictor drugs (PGF2 alpha, histamine and adrenaline) increase tonic tension without modifying the frequency of clonic activity. It is suggested that spontaneous contractility may be the expression of myogenic excitability related to the regulation of fetal placental blood flow.

Critical closing pressure in the fetal vessel of the human placenta in vitro. II. Compared effects of a beta adrenergic substance, Salbutamol, on the critical closing pressure and vascular resistance.

Salbutamol effects upon the fetal vessels of the human placenta were studied in vitro, comparing the changes induced upon the critical closing pressure (CCP) and viscous resistance (R). Four normal full-term placentas were used. In each of them, 4 cotyledonary areas were perfused, thus obtaining a total of 16 measurements for the observation of spontaneous variations (blank), by perfusion with Krebs solution, and the same amount for the variations due to Salbutamol. The concentration used was 10 microgram/ml, with a 4.25 ml/min flow. The relative effect of Salbutamol upon CCP was its decrease--30.4% against a relative spontaneous variation of --3.6%. The mean relative effect upon R was much lower, --9.4%. against a mean relative spontaneous variation of + 3.3%. The advantages of using CCP instead of R as a parameter of vascular contractility are discussed. Furthermore, Salbutamol is suggested to be useful in improving fetal placental circulation.