Potassium channels mediate nitric oxide-induced vasorelaxation in arteries supplying colon cancer

Aberrant vascular function and cancer growth are closely related, with nitric oxide (NO) being a key factor in vascular tone regulation. This study provides Novel insights into the distinctive mechanisms underlying cancer-associated vascular dysfunction by investigating the involvement of potassium (K⁺) channels in NO-mediated vasorelaxation within arteries supplying colon cancer.

Arterial segments from colon cancer patients were isolated and sectioned into rings, these rings were mounted in an organ bath filled with Krebs' solution and maintained at 37°C. Isometric tension recordings were obtained using a force transducer connected to a PowerLab Data Acquisition System. Arterial segments were pre-incubated with a variety of K⁺ channel blockers, both individually and in combination, including glibenclamide (GLIB), barium chloride (BaCl₂), tetraethylammonium (TEA), and 4-aminopyridine (4-AP). Concentration-response curves were designed to evaluate how K⁺ channel blocking affected the vasodilation caused by NO.

Sodium nitroprusside (SNP) induced vasorelaxation in arterial rings from colon cancer, influenced by specific K+ channels. Pre-incubation with TEA significantly reduced Emax to 60.22 ± 8.14 %, compared to 124.91 ± 15.07 % in controls, while GLIB decreased Emax to 113.10 ± 3.87 %. BaCl2 and 4-AP further diminished relaxation, and combined K⁺ channel blockers showed complex, non-additive effects. Distinct contributions of K_Ca and K_V channels to NO-induced vasodilation were elucidated. Additionally, interaction between NO and L-type calcium (Ca²⁺) channels suggested a novel vasorelaxation mechanism in cancerous tissues.

This research offers new perspectives on the intricate relationship between vascular biology and cancer development, emphasizing the promise of targeting potassium channels to address vascular abnormalities in cancer.