Prolonged Exposure to Lopinavir Impairs Endothelium-dependent Hyperpolarization-mediated Relaxation in Rat Mesenteric Arteries

Abstract

Protease inhibitors (PIs) and non-nucleoside reverse transcriptase inhibitors are effective antiretroviral drugs, but their use is associated with a high incidence of cardiovascular disease. As vascular dysfunction precedes cardiovascular events, this study aimed to examine the vascular effects of clinically used PIs (indinavir, lopinavir, nelfinavir, ritonavir, saquinavir, and tipranavir) and non-nucleoside reverse transcriptase inhibitors (efavirenz and nevirapine). Rat mesenteric arteries were suspended in conventional organ chambers for isometric tension recording. Efavirenz, indinavir, nelfinavir, ritonavir, and tipranavir, but not saquinavir and nevirapine, caused endothelium-independent relaxations. Lopinavir induced both endothelium-dependent and -independent relaxations; the former was inhibited by nitric oxide (NO) synthase inhibitor. Incubation with lopinavir for 24 hours reduced relaxations attributable to endothelium-derived hyperpolarization. Relaxations to the adenosine triphosphate-sensitive potassium (K(ATP)) channel opener, levcromakalim, but not those to the NO donor, sodium nitroprusside, were also inhibited. Western blotting indicated that the protein expressions of intermediate (IK(Ca)) and small (SK(Ca)) conductance calcium-activated potassium channels and K(ATP) channel were reduced in mesenteric arteries incubated with lopinavir for 24 hours. In conclusion, lopinavir differs from other PIs in that it acutely induces endothelium-derived NO-mediated relaxation. However, prolonged exposure to lopinavir impairs relaxations, likely by reducing the expressions of IK(Ca), SK(Ca), and K(ATP) channels.

Reduced activity of SKCa and Na‐K ATPase underlies the accelerated impairment of EDH‐type relaxations in mesenteric arteries of aging spontaneously hypertensive rats

“…,b; Félétou and Vanhoutte ; Yeung et al. ). Therefore, the residual relaxations to acetylcholine observed here in mesenteric arteries incubated with indomethacin and L‐NAME can be attributed to EDH, as they were abolished by the combination of IK Ca and SK Ca blockers, TRAM‐34 and UCL 1684 (Fig.…”

“…; Yeung et al. ). Some preparations were treated with various pharmacological agents, including 1‐​[(2‐​chlorophenyl)​diphenylmethyl]​‐​1H‐​pyrazole [TRAM‐34, intermediate‐conductance calcium‐activated potassium (IK Ca ) channel blocker, 5 × 10 −7 M (Zou et al.…”

“…; Yeung et al. )], 6,12,19,20,25,26‐​hexahydro‐5,27:13,18:21,24‐​trietheno‐​11,7‐​metheno‐​7H‐​dibenzo[b,m]​[1,5,12,16]​tetraazacyclotricosine‐​5,13‐​diium ditrifluoroacetate hydrate [UCL 1684, small‐conductance calcium‐activated potassium (SK Ca ) channel blocker, 5 × 10 −7 M (Zou et al. ; Yeung et al.…”

“…; Yeung et al. )], ouabain [sodium‐potassium ATPase (Na‐K ATPase) inhibitor, 10 −3 M (Doughty et al. )], barium chloride [inwardly‐rectifying potassium (K IR ) channel blocker, 3 × 10 −5 M (Doughty et al.…”

Kaempferol enhances endothelium‐dependent relaxation in the porcine coronary artery through activation of large‐conductance Ca2+‐activated K+ channels

“…After a stable and sustained contraction was achieved with U46619, the relaxing agent, bradykinin (10 −11 to 10 −6 M) or sodium nitroprusside (10 −9 to 10 −4 M), was added to the rings in cumulative manner to obtain concentration–relaxation curves. In order to determine the mechanism of actions of kaempferol, some porcine coronary arterial rings were incubated with N ω ‐nitro‐L‐arginine methyl ester (L‐NAME, inhibitor of NOSs, 10 −4 M; Ng et al ., ), 1 H ‐[1,2,4]oxadiazolo[4,2‐a] quinoxalin‐1‐one (ODQ, inhibitor of soluble GC, 10 −5 M; Chan et al ., ), iberiotoxin [inhibitor of large‐conductance calcium‐activated potassium channel (K Ca 1.1), 10 −7 M; Liang et al ., ], charybdotoxin [inhibitor of K Ca 1.1 and intermediate‐conductance calcium‐activated potassium channel (K Ca 3.1), 10 −7 M; Ng et al ., ], 1‐[(2‐chlorophenyl)diphenylmethyl]‐1H‐pyrazole (TRAM‐34, inhibitor of K Ca 3.1, 10 −6 M; Yeung et al ., ), 6,12,19,20,25,26‐hexahydro‐5,27:13,18:21,24‐trietheno‐11,7‐metheno‐7H‐dibenzo[b,n][1,5,12,16]tetraazacyclotricosine‐5,13‐diium dibromide (UCL 1684), inhibitor of small‐conductance calcium‐activated potassium channel (K Ca 2.3), 10 −6 M; Yeung et al ., ], apamin (inhibitor of K Ca 2.3, 10 −6 M; Ng et al ., ) and/or tetraethylammonium chloride [TEA, non‐selective inhibitor of calcium‐activated potassium channel (K Ca ), 10 −3 M; Shimizu et al ., ], in the absence and presence of kaempferol (3 × 10 −6 M) for 30 min, before obtaining a sustained contraction with U46619 followed by relaxation to cumulative addition of bradykinin or sodium nitroprusside.…”