Response to Sympathoinhibitory effect of diltiazem and prevention of aneurysm formation.

Response to Sympathoinhibitory Effect of Diltiazem and Prevention of Aneurysm Formation We thank Dr Tsuda1 for the important remark and his interest in our work. Unfortunately, we did not perform measurements on the effect of diltiazem on sympathetic nerve activity in our study and as mechanism of action of the drug we observed some direct inhibitory action on the inflammatory activity of cultured monocytic cells.2 Nevertheless, we agree that our proposed mechanism is probably not the only one operative in the highly complex model of angiotensin II–induced aneurysm formation in ApoE−/− mice3 and that diltiazem in vivo may have additional effects. A role of the sympathetic nervous system in vascular inflammatory processes is established,4 and in high concentrations diltiazem is known to inhibit neuronal voltagedependent calcium channels.5 Thus, the mechanism proposed by Dr Tsuda is indeed plausible to contribute to the antianeurysmal effect of Diltiazem.