Testosterone-induced relaxation of coronary arteries: activation of BKCa channels via the cGMP-dependent protein kinase

Androgens are reported to have both beneficial and detrimental effects on human cardiovascular health. The aim of this study was to characterize nongenomic signaling mechanisms in coronary artery smooth muscle (CASM) and define the ionic basis of testosterone (TES) action. TES-induced relaxation of endothelium-denuded porcine coronary arteries was nearly abolished by 20 nM iberiotoxin, a highly specific inhibitor of large-conductance, calcium-activated potassium (BKCa) channels. Molecular patch-clamp studies confirmed that nanomolar concentrations of TES stimulated BKCa channel activity by ∼100-fold and that inhibition of nitric oxide synthase (NOS) activity by NG-monomethyl-l-arginine nearly abolished this effect. Inhibition of nitric oxide (NO) synthesis or guanylyl cyclase activity also attenuated TES-induced coronary artery relaxation but did not alter relaxation due to 8-bromo-cGMP. Furthermore, we detected TES-stimulated NO production in porcine coronary arteries and in human CASM cells via stimulation of the type 1 neuronal NOS isoform. Inhibition of the cGMP-dependent protein kinase (PKG) attenuated TES-stimulated BKCa channel activity, and direct assay determined that TES increased activity of PKG in a concentration-dependent fashion. Last, the stimulatory effect of TES on BKCa channel activity was mimicked by addition of purified PKG to the cytoplasmic surface of a cell-free membrane patch from CASM myocytes (∼100-fold increase). These findings indicate that TES-induced relaxation of endothelium-denuded coronary arteries is mediated, at least in part, by enhanced NO production, leading to cGMP synthesis and PKG activation, which, in turn, opens BKCa channels. These findings provide a molecular mechanism that could help explain why androgens have been reported to relax coronary arteries and relieve angina pectoris.

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Preservation of nitric oxide-induced relaxation of porcine coronary artery: roles of the dimers of soluble guanylyl cyclase, phosphodiesterase type 5, and cGMP-dependent protein kinase

Pflügers Archiv - European Journal of Physiology ◽

10.1007/s00424-014-1441-2 ◽

2014 ◽

Vol 466 (10) ◽

pp. 1999-2008 ◽

Cited By ~ 4

Author(s):

Juan Liu ◽

Zhengju Chen ◽

Liping Ye ◽

Huixia Liu ◽

Dou Dou ◽

...

Keyword(s):

Nitric Oxide ◽

Coronary Artery ◽

Protein Kinase ◽

Guanylyl Cyclase ◽

Soluble Guanylyl Cyclase ◽

Dependent Protein Kinase ◽

Porcine Coronary Artery ◽

Cgmp Dependent Protein Kinase ◽

Dependent Protein ◽

Phosphodiesterase Type

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Nitric oxide reduces flow-induced superoxide production via cGMP-dependent protein kinase in thick ascending limbs

AJP Renal Physiology ◽

10.1152/ajprenal.90707.2008 ◽

2009 ◽

Vol 296 (5) ◽

pp. F1061-F1066 ◽

Cited By ~ 12

Author(s):

Nancy J. Hong ◽

Jeffrey L. Garvin

Keyword(s):

Nitric Oxide ◽

Protein Kinase ◽

No Synthase ◽

Minor Role ◽

No Production ◽

Dependent Protein Kinase ◽

Cgmp Dependent Protein Kinase ◽

Dependent Protein ◽

Ly 83583 ◽

Reduced Flow

We have shown that increased luminal flow induces O2− and nitric oxide (NO) production in thick ascending limbs (TALs). However, the interaction of flow-stimulated NO and O2− in TALs is unclear. We hypothesized that NO inhibits flow-induced O2− production in TALs via cGMP-dependent protein kinase (PKG). We measured flow-stimulated O2− production in rat TALs using dihydroethidium in the absence and presence of l-arginine (0.3 mM), the substrate for NO synthase. The addition of l-arginine reduced flow-induced net O2− production from 68 ± 9 to 17 ± 4 AU/s ( P < 0.002). The addition of the NO synthase inhibitor NG-nitro-l-arginine methyl ester (l-NAME; 5 mM) in the presence of l-arginine stimulated production (l-arginine: 15 ± 4 AU/s vs. l-arginine + l-NAME: 63 ± 7 AU/s; P < 0.002). The guanylate cyclase inhibitor LY-83583 (10 μM) also enhanced flow-induced net O2− production in the presence of l-arginine (l-arginine: 7 ± 4 AU/s vs. l-arginine + LY-83583: 53 ± 7 AU/s; P < 0.01). In the presence of LY-83583, l-arginine only reduced flow-induced net O2− by 36% (LY-83583: 80 ± 7 AU/s vs. LY-83583 + l-arginine: 51 ± 3 AU/s; P < 0.006). The cGMP analog dibutyryl (db)-cGMP reduced flow-induced net O2− from 39 ± 9 to 7 ± 3 AU/s ( P < 0.03). The PKG inhibitor KT-5823 (5 μM) partially restored flow-induced net O2− in the presence of l-arginine (l-arginine: 4 ± 4 AU/s vs. l-arginine + KT-5823: 32 ± 9 AU/s; P < 0.03) and db-cGMP (db-cGMP: 9 ± 7 AU/s vs. db-cGMP + KT-5823: 54 ± 5 AU/s; P < 0.01). Phosphodiesterase II inhibition had no effect on arginine-inhibited O2− production. We conclude that 1) NO reduces flow-stimulated O2− production, 2) this occurs primarily via the cGMP/PKG pathway, and 3) O2− scavenging by NO plays a minor role.

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