Comment: Calcium signal transduction in endothelial cells in response to various mediators is a major pathway in determining vasoactive physiologic and pharmacologic responses. Because halothane and isoflurane have very different blood pressure effects, it is logical to hypothesize that they may have different effects on the peripheral vascular endothelium. This study demonstrates that halothane interferes with the calcium pathway stimulated by bradykinin but isoflurane does not. The actual mechanism for this interference was not determined. Whether this interference actually accounts for the different peripheral vascular effects of the inhalation anesthetics will require further investigation.