Voltage-gated potassium channel proteins and stereoselective S-nitroso-l-cysteine signaling.

S-nitroso-l-cysteine (L-CSNO) behaves as a ligand. Its soluble guanylate cyclase-independent (sGC-independent) effects are stereoselective - that is, not recapitulated by S-nitroso-d-cysteine (D-CSNO) - and are inhibited by chemical congeners. However, candidate L-CSNO receptors have not been identified. Here, we have used 2 complementary affinity chromatography assays - followed by unbiased proteomic analysis - to identify voltage-gated K+ channel (Kv) proteins as binding partners for L-CSNO. Stereoselective L-CSNO-Kv interaction was confirmed structurally and functionally using surface plasmon resonance spectroscopy; hydrogen deuterium exchange; and, in Kv1.1/Kv1.2/Kvß2-overexpressing cells, patch clamp assays. Remarkably, these sGC-independent L-CSNO effects did not involve S-nitrosylation of Kv proteins. In isolated rat and mouse respiratory control (petrosyl) ganglia, L-CSNO stereoselectively inhibited Kv channel function. Genetic ablation of Kv1.1 prevented this effect. In intact animals, L-CSNO injection at the level of the carotid body dramatically and stereoselectively increased minute ventilation while having no effect on blood pressure; this effect was inhibited by the L-CSNO congener S-methyl-l-cysteine. Kv proteins are physiologically relevant targets of endogenous L-CSNO. This may be a signaling pathway of broad relevance.

Dehydroepiandrosterone Supplementation May Benefit Women with Asthma Who Have Low Androgen Levels: A Pilot Study.

INTRODUCTION: Among individuals with severe asthma, FEV1 is low in individuals with low dehydroepiandrosterone (DHEA) sulfate (DHEAS) levels. In the Severe Asthma Research Program (SARP), no women with DHEAS > 200 µg/dL had an FEV1 < 60% predicted. DHEA has benefited patients with COPD and pulmonary hypertension in small trials. Therefore, we hypothesized that DHEA supplementation may improve FEV1 in asthmatic women with low DHEAS. METHODS: Premenopausal, nonsmoking, otherwise healthy women, 18-50 years old, with mild or moderate asthma and baseline FEV1 > 60% predicted received 100 mg DHEA orally every 12 h for 2 weeks. Spirometry and DHEAS were measured at the initial visit and 2 weeks later, after completion of DHEA treatment. Based on our previous work, the primary outcome variable for this pilot study was post-albuterol spirometry in the low-DHEAS group. Subjects also continued their other routine asthma management. RESULTS: Serum DHEAS increased with DHEA treatment in women with starting DHEAS < 200 µg/dL: this increase was from 71 ± 23 to 725 ± 295 µg/dL (n = 10; p = 0.0001). The increase in the high-DHEAS group was smaller. Post-albuterol FEV1 increased by 51 mL, from 3.026 ± 0.5 to 3.077 ± 0.49 L (n = 10; p = 0.034 by paired t test, significant after Bonferroni), in women with low DHEAS. In the high-DHEAS group (baseline DHEAS ≥ 200 µg/dl), post-albuterol FEV1 did not change significantly (n = 3, p = NS). Three subjects were excluded: one had comorbid COPD, one could not perform spirometry, and one did not take the DHEA. There were no adverse effects of DHEA treatment in this trial. CONCLUSIONS: Endocrine treatments (corticosteroids) are a mainstay of anti-inflammatory management for moderate and severe asthma. Their use has improved asthma outcomes. Androgens also reduce airway inflammation and promote airway smooth muscle relaxation, but are rarely used clinically for asthma treatment. Our results suggest that the over-the-counter steroid DHEA may improve lung function in asthma outcomes among women with DHEAS < 200 ug/dL.