Contribution of BKCa channels to local metabolic coronary vasodilation: effects of metabolic syndrome
exercise; Physiology; Cardiovascular System & Cardiology; nitric-oxide; blood flow; coronary blood flow; smooth-muscle-cells; insulin-resistance; cardiovascular-disease; pigs; ca2+-activated k+ channels; induced relaxation; Ossabaw miniature swine; A; diabetic dyslipidemic; exercising dogs; myocardial oxygen consumption; myocardial-metabolism; penitrem
Borbouse L, Dick GM, Payne GA, Payne BD, Svendsen MC, Neeb ZP, Alloosh M, Bratz IN, Sturek M, Tune JD. Contribution of BKCa channels to local metabolic coronary vasodilation: effects of metabolic syndrome. Am J Physiol Heart Circ Physiol 298: H966-H973, 2010. First published December 31, 2009; doi:10.1152/ajpheart.00876.2009.-This investigation was designed to examine the hypothesis that impaired function of coronary microvascular large-conductance Ca2+-activated K+ (BKCa) channels in metabolic syndrome (MetS) significantly attenuates the balance between myocardial oxygen delivery and metabolism at rest and during exercise-induced increases in myocardial oxygen consumption (M(V) over dotO(2)). Studies were conducted in conscious, chronically instrumented Ossabaw swine fed a normal maintenance diet (11% kcal from fat) or an excess calorie atherogenic diet (43% kcal from fat, 2% cholesterol, 20% kcal from fructose) that induces many common features of MetS. Data were collected under baseline/resting conditions and during graded treadmill exercise before and after selective blockade of BKCa channels with penitrem A (10 mu g/kg iv). We found that the exercise-induced increases in blood pressure were significantly elevated in MetS swine. No differences in baseline cardiac function or heart rate were noted. Induction of MetS produced a parallel downward shift in the relationship between coronary venous PO2 and M(V) over dotO(2) (P < 0.001) that was accompanied by a marked release of lactate (negative lactate uptake) as M(V) over dotO(2) was increased with exercise (P < 0.005). Inhibition of BKCa channels with penitrem A did not significantly affect blood pressure, heart rate, or the relationship between coronary venous PO2 and M(V) over dotO(2) in lean or MetS swine. These data indicate that BKCa channels are not required for local metabolic control of coronary blood flow under physiological (lean) or pathophysiological (MetS) conditions. Therefore, diminished function of BKCa channels does not contribute to the impairment of myocardial oxygen-supply demand balance in MetS.
Borbouse L; Dick G M; Payne G A; Payne B D; Svendsen M C; Neeb Z P; Alloosh M; Bratz I N; Sturek M; Tune J D
American Journal of Physiology-Heart and Circulatory Physiology
2010
2010-03
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1152/ajpheart.00876.2009" target="_blank" rel="noreferrer noopener">10.1152/ajpheart.00876.2009</a>
Fluorocholesterols, In Contrast To Hydroxycholesterols, Exhibit Interfacial Properties Similar To Cholesterol
a; bile-acids; Biochemistry & Molecular Biology; condensation; enzyme-catalyzed oxidation; isotherm; monolayers; orientation; orphan nuclear receptor; phosphatidylcholine; phosphatidylcholines; reductase-activity; side-chain; spectroscopic imaging; sterol synthesis; surface balance; surface potential
We used an automated Langmuir-Pockels surface balance to characterize the air-water interfacial properties of cholesterol (CH) and its derivatives with hydrophilic OH and F substitutions at isologous sites on the sterol body or side chain. We studied 6-fluorocholesterol, 25-fluorocholesterol, 25,26,26,26,27,27,27-heptafluorocholesterol, 7 alpha-hydroxycholesterol, 7 beta-hydroxycholesterol, 25-hydroxycholesterol and 27-hydroxycholesterol, alone and in mixtures with 1-palmitoyl-2-oleoyl-sn-3-glycero-phosphocholine (POPC). Pressure-area isotherms of the fluorocholesterols were essentially indistinguishable from CH and all condensed POPC monomolecular layers (monolayers) to variable degrees. Both nucleus-substituted hydroxycholesterols formed expanded monolayers, with lift-offs from baseline 22-26 Angstrom(2)/molecule larger than CH, suggesting interfacial tilting; furthermore, in binary mixtures, they condensed POPC monolayers less than CH, In contrast, the side chain hydroxylated CHs were oriented horizontally in the interface at large molecular areas, and became vertical below 140 Angstrom(2)/molecule with the side chain-OH rather than 3-OH group anchored in the subphase, as evidenced by low collapse pressures and smaller molecular areas than CH. Both side chain hydrocholesterols expanded POPC monolayers at molar ratios <30%, but induced condensation with higher ratios, suggesting that OH-acyl chain (POPC) repulsion is superceded at higher mole fractions by lateral phase separation and intersteroidal H-bonding. These studies predict that fluorocholesterols should exhibit intramembrane spatial occupancy nearly identical to CH, whereas nucleus and especially side chain hydroxycholesterols will perturb membrane lipid packing notably.
Kauffman J M; Westerman P W; Carey M C
Journal of Lipid Research
2000
2000-06
Journal Article or Conference Abstract Publication
n/a