Alterations in KATP and KCa channel function in cerebral arteries of insulin-resistant rats

1 Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157-1083; and 2 Institute of Human Physiology and Clinical Experimental Research, Semmelweis University, Budapest, Hungary 1082 We examined whether insulin resistance alters the function of ATP-dependent and Ca 2+ -activated K + channels (K ATP and K Ca channels, respectively) in pressurized isolated middle cerebral arteries (MCAs) from fructose-fed insulin-resistant (IR) and control rats. Blockade of K Ca channels with tetraethylammonium chloride (TEA, 2.5 mM) or iberiotoxin (IBTX, 0.1 µM) increased the spontaneously developed tone in control MCAs by 10.5 ± 1.3% ( n = 10) and 13.3 ± 2.3% ( n = 6), respectively. In the IR arteries, TEA induced similar constrictions (8.0 ± 1.1%, n = 10), but IBTX constricted the IR arteries by only 3.1 ± 0.9% ( n = 8; P