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>
Masticatory motor patterns in ungulates: A quantitative assessment of jaw-muscle coordination in goats, alpacas and horses
electromyography; emg; force; fusion; mandibular symphysis; masseter muscle; movements; pigs; Zoology
We investigated patterns of jaw-muscle coordination during rhythmic mastication in three species of ungulates displaying the marked transverse jaw movements typical of many large mammalian herbivores. In order to quantify consistent motor patterns during chewing, electromyograms were recorded from the superficial masseter, deep masseter, posterior temporalis and medial pterygoid muscles of goats, alpacas and horses. Timing differences between muscle pairs were evaluated in the context of an evolutionary model of jaw-muscle function. In this model, the closing and food reduction phases of mastication are primarily controlled by two distinct muscle groups, triplet I (balancing-side superficial masseter and medial pterygoid and working-side posterior temporalis) and triplet II (working-side superficial masseter and medial pterygoid and balancing-side posterior temporalis), and the asynchronous activity of the working- and balancing-side deep masseters. The three species differ in the extent to which the jaw muscles are coordinated as triplet I and triplet II. Alpacas, And to a lesser extent, goats, exhibit the triplet pattern whereas horses do not. In contrast, all three species show marked asynchrony of the working-side and balancing-side deep masseters, with jaw closing initiated by the working-side muscle and the balancing-side muscle firing much later during closing. However, goats differ from alpacas and horses in the timing of the balancing-side deep masseter relative to the triplet II muscles. This study highlights interspecific differences in the coordination of jaw muscles to influence transverse jaw movements and the production of bite force in herbivorous ungulates.
Williams S H; Vinyard C J; Wall C E; Hylander W L
Journal of Experimental Zoology Part a-Ecological Genetics and Physiology
2007
2007-04
Journal Article
<a href="http://doi.org/10.1002/jez.a.362" target="_blank" rel="noreferrer noopener">10.1002/jez.a.362</a>