Effects of Eicosanoids on Vascular Smooth Muscle

Mechanism of the Effects of Eicosanoids on Vascular Smooth Muscle 

In vitro, eicosanoids are produced by all layers of the arterial wall (see above). Endogenous production of prostaglandins by smooth muscle is related partly to tone, for example gut, umbilical artery, ductus arteriosus and coronary artery (Eckenfels and Vane 1972, Tuvemo and Wide 1973, Coceani et al. 1975, Kalsner 1975). Clinically this has led to the successful use of indomethacin for the treatment of patent ductus arteriosus. To what extent do changes in smooth muscle contraction modulate endogenous production of eicosanoids by the smooth muscle cells Does generation of eicosanoids within the arterial wall either mediate or modulate the actions of other vasoactive agents on arterial smooth muscle Clearly these questions are interlinked. 

Dawson and Irvine (1978) noted that in many of those tissues in which physiological stimuli caused activation of phosphatidyl-inositol turnover, the same stimuli caused an increase in prostaglandin release. Such activation of phosphatidyl-inositol turnover and augmented production of 

Many of the effects of eicosanoids are calcium dependent and their structure has stimulated speculation that they may act as calcium iono-phores (Horton 1969, Harris et al. 1979, Kirtland and Baum 1972). With reference to excitation-contraction coupling in smooth muscle, some workers have found that prostaglandin-induced smooth muscle contraction is dependent on extracellular calcium (Smith et al. 1981, Godfraind and Miller 1982) whereas others have suggested that such a contraction is mediated by a release of calcium from intracellular stores (McNamara et al. 

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