A proposed mechanism of bupivacaine-induced contraction of human umbilical artery smooth muscle cells.

This in vitro study using ring preparations of human umbilical vessels and cultured human umbilical artery smooth muscle cells was designed to determine: (a) the mechanism of bupivacaine-induced contraction of ring preparations, and (b) whether similar concentrations of bupivacaine release Cal(2+) in cultured smooth muscle cells. Isometric tension was recorded from ring preparations of human umbilical veins and arteries in an isolated tissue chamber. Separate fluorescence and electrophysiology studies were done with cultured human umbilical artery smooth muscle cells.

The response of umbilical vessels, with and without vascular endothelium, to local anesthesia in low PO2 and hypercarbia.

Background And Objectives: Human umbilical vessels are sensitive to local anesthetic agents as well as to a variety of other exogenous and endogenous substances. Changes in blood gases such as hypoxia and hypercarbia may alter these responses. This study examined the effects of local anesthetic agents under these conditions and how the effects are related to the vascular endothelium.

Umbilical vessels endothelium and vascular reactivity.

In vitro preparations of isolated umbilical vessels are ideal for the study of vasoactive substances. These vessels display vascular reactivity in response to numerous substances, although the mechanism of action of many of these agents is unknown. The present study was undertaken to study the role of the endothelium in the vasoactivity of these preparations, and to examine their cellular integrity.

Vasoactive actions of local anaesthetics on human isolated umbilical veins and arteries.

1. An in vitro study, using helical preparations of human umbilical arteries and veins obtained from healthy women at term pregnancy, was designed to determine: (a) whether three local anaesthetics commonly utilized in obstetric anaesthesia (bupivacaine, 2-chloroprocaine, and lignocaine) can induce contraction or relaxation of resting umbilical vessels; (b) whether these agents can induce contraction or relaxation of umbilical vessels which have been previously induced to contract by a known activator, potassium chloride (KCl); and (c) the relative potency of these agents as compared to KCl. 2.

Neonatal thyroid function and anaesthesia.

Thyroid function in the neonate and its response to hexobarbitone anaesthesia were studied in newborn Wistar rats between 24 h and 42 days old. 14C-labelled mixed with unlabelled hexobarbitone was injected i.p.