Figure 2. Reverse-phase HPLC chromatograph illustrating the cytochrome P450 metabolism of [¹⁴C]arachidonic acid ([¹⁴C]AA) in isolated cat cerebral VSMCs.

A, control chromatogram demonstrating the separation of arachidonic acid metabolites formed by cat VSMCs incubated with [¹⁴C]AA as described in the Methods. The peak eluting at 22.4 min has a retention time similar to that of standard 20-HETE shown in B. B, chromatogram demonstrating the elution profile of authentic ¹⁴C-labelled 20-HETE alone which eluted at 22.4 min. C, elution profile of P450 metabolites of AA demonstrating the effect of 17-octadecynoic acid (1 μm, 17-ODYA), a mechanism-based suicide substrate inhibitor of P450 ω-hydroxylase on P450 metabolism of exogenous [¹⁴C]AA by VSMCs. 17-ODYA (1 μm) blocked the formation of the major P450 metabolite with a retention time of 22.4 min. PGs, prostaglandins; EETs, epoxyeicosatrienoic acids.