The KCa3.1 channel blocker TRAM-34 and minocycline prevent fructose-induced hypertension in rats

• Published in: American journal of hypertension Vol. 37; no. 12; pp. 995 - 1002
• Main Authors: Hamad, A, Ozkan, M H
• Format: Journal Article
• Language: English
• Published: United States 15-11-2024
• Subjects: fructose; TRAM-34; rat; hypertension; minocycline
• ISSN: 0895-7061; 1941-7225; 1941-7225
• DOI: 10.1093/ajh/hpae115

High fructose consumption increases blood pressure through microglia-related neuroinflammation in rats. Since intermediate-conductance calcium-activated potassium channels (KCa3.1) potentiates microglial reactivity, we examined whether the pretreatment with the KCa3.1 channel blocker TRAM-34 or minocycline prevents hypertension development in fructose-fed rats.
The study involved male Wistar rats that were given either a high fructose (10% in drinking water) or a tap water for 21 days. Fructose groups also received minocycline or TRAM-34 systemically for 21 days. We measured systolic and diastolic blood pressure (SBP and DBP), heart rate (HR) periodically with tail-cuff; proinflammatory cytokines and insulin levels in plasma via ELISA, and neuroinflammatory markers in the nucleus tractus solitarii (NTS) by qPCR at the end of 21 days. We also examined endothelium-dependent hyperpolarization (EDH)-type vasorelaxations in isolated mesenteric arteries of the rats ex vivo.
SBP, DBP, and HR increased in the fructose group. Both minocycline and TRAM-34 significantly prevented these increases. Fructose intake also increased plasma IL-6, IL-1β, TNF-α, and insulin levels, whereas pretreatment with TRAM-34 prevented these increases as well. Iba-1, but not CD86 levels were significantly higher in the NTS samples of fructose-fed hypertensive rats which implied microglial proliferation. EDH-type vasorelaxations mediated by endothelial KCa3.1 attenuated in the fructose group; however, TRAM-34 did not cause further deterioration in the relaxations.
TRAM-34 is as effective as minocycline in preventing fructose-induced hypertension without interfering with the EDH-type vasodilation. Furthermore, TRAM-34 relieves high fructose-associated systemic inflammation.