Enhancement of capsaicin-induced contraction of guinea-pig tracheal smooth muscle by vanadate.

Contractions of guinea-pig isolated tracheal smooth muscle by submaximal capsaicin (0.1 microM) were enhanced by 43% (P less than 0.01) after vanadate (10 microM for 10 min) preincubation.

Airways hyperreactivity and bronchoconstriction induced by vanadate in the guinea-pig.

1 The characteristics of vanadate-induced bronchoconstriction and airways hyperreactivity were observed in spontaneously breathing anaesthetized guinea-pigs by measurement of airways resistance (Raw) and dynamic lung compliance (Cdyn). Vanadate (0.3-3 mg kg-1 i.

Smooth muscle contractility and changes in histaminergic mechanisms in the pig trachea during development.

Maximal contractile reactivity was compared in isolated tracheas from different sized (aged) pigs. Maximum force and tension to histamine declined by approximately 10-fold in tracheas from 150-200 kg pigs compared to 30 kg animals, whereas acetylcholine-induced contractions were little changed. Furthermore, contractions to Ca2+ in chemically skinned muscle were not different in different sized animals.

Inhibition of cycling and noncycling cross bridges in skinned smooth muscle by vanadate.

Vanadate (Vi, 3-300 microM) reversibly inhibited force development elicited by micromolar Ca2+ in membrane-skinned fibers of smooth muscle from taenia coli and trachea of guinea pig. When relaxed fibers were preincubated with Vi, the contraction to Ca2+ was characterized by a peak response followed by a lower steady-state phase. The peak phase depended on the rate of contraction and the [Vi]and was absent after Vi incubation during a previous contraction.

Mechanism of vanadate-induced contraction of airways smooth muscle of the guinea-pig.

The characteristics of vanadate-induced contraction of airways smooth muscle are described in isolated preparations of guinea-pig central and peripheral airways. Vanadate (1-1000 microM) induced sustained contractions of trachea and lung parenchymal strips within 1 min of challenge. It was more potent (P less than 0.