KCa channels are major contributors to ATP-induced cutaneous vasodilation in healthy older adults

• Published in: Microvascular research 2021-01, Vol.133, p.104096, Article 104096
• Main Authors: McGarr, Gregory W., Muia, Caroline M., Saci, Samah, Fujii, Naoto, Kenny, Glen P.
• Format: Article
• Language: English
• Subjects: Heat loss; Microdialysis; Purinergic; Skin blood flow; Thermoregulation
• ISSN: 0026-2862; 1095-9319
• DOI: 10.1016/j.mvr.2020.104096

To examine the contributions of calcium-activated K+ (KCa) channels and nitric oxide synthase (NOS) to adenosine triphosphate (ATP)-induced cutaneous vasodilation in healthy older adults. In eleven older adults (69 ± 2 years, 5 females), cutaneous vascular conductance, normalized to maximum vasodilation (%CVCmax) was assessed at four dorsal forearm skin sites that were continuously perfused with either 1) lactated Ringer solution (Control), 2) 50 mM tetraethylammonium (TEA, KCa channel blocker), 3) 10 mM Nω-nitro-L-arginine (L-NNA, NOS inhibitor), or 4) combined 50 mM TEA +10 mM L-NNA, via microdialysis. Local skin temperature was fixed at 33 °C at all sites with local heaters throughout the protocol while the cutaneous vasodilator response was assessed during coadministration of ATP (0.03, 0.3, 3, 30, 300 mM; 20 min per dose), followed by 50 mM sodium nitroprusside and local skin heating to 43 °C to achieve maximum vasodilation (20–30 min). Blockade of KCa channels blunted %CVCmax relative to Control from 0.3 to 300 mM ATP (All P