Impaired function of coronary BKCa channels in metabolic syndrome
obesity; Physiology; Cardiovascular System & Cardiology; channels; smooth-muscle-cells; circulation; cardiovascular-disease; Ion channels; beta-1 subunit; activated potassium; arteriolar dilation; blood flow; ca2+-activated k+ channels; currents; diabetic fatty rats; induced relaxation; large-conductance; outward
Borbouse L, Dick GM, Asano S, Bender SB, Dincer UD, Payne GA, Neeb ZP, Bratz IN, Sturek M, Tune JD. Impaired function of coronary BKCa channels in metabolic syndrome. Am J Physiol Heart Circ Physiol 297: H1629-H1637, 2009. First published September 11, 2009; doi:10.1152/ajpheart.00466.2009.-The role of large-conductance Ca2+-activated K+ (BKCa) channels in regulation of coronary microvascular function is widely appreciated, but molecular and functional changes underlying the deleterious influence of metabolic syndrome (MetS) have not been determined. Male Ossabaw miniature swine consumed for 3-6 mo a normal diet (11% kcal from fat) or an excess-calorie atherogenic diet that induces MetS (45% kcal from fat, 2% cholesterol, 20% kcal from fructose). MetS significantly impaired coronary vasodilation to the BKCa opener NS-1619 in vivo (30-100 mu g) and reduced the contribution of these channels to adenosine-induced microvascular vasodilation in vitro (1-100 mu M). MetS reduced whole cell penitrem A (1 mu M)-sensitive K+ current and NS-1619-activated (10 mu M) current in isolated coronary vascular smooth muscle cells. MetS increased the concentration of free intracellular Ca2+ and augmented coronary vasoconstriction to the L-type Ca2+ channel agonist BAY K 8644 (10 pM-10 nM). BKCa channel alpha and beta(1) protein expression was increased in coronary arteries from MetS swine. Coronary vascular dysfunction in MetS is related to impaired BKCa channel function and is accompanied by significant increases in L-type Ca2+ channel-mediated coronary vasoconstriction.
Borbouse L; Dick G M; Asano S; Bender S B; Dincer U D; Payne G A; Neeb Z P; Bratz I N; Sturek M; Tune J D
American Journal of Physiology-Heart and Circulatory Physiology
2009
2009-11
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1152/ajpheart.00466.2009" target="_blank" rel="noreferrer noopener">10.1152/ajpheart.00466.2009</a>
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>
Microvascular Function/dysfunction Downstream A Coronary Stenosis
artery disease; blood-flow; ca2+-activated k+ channels; Coronary microcirculation; coronary stenosis; endothelial dysfunction; flow-induced dilation; function; iib/iiia receptor blockade; left-ventricular wall; myocardial ischemia; myocardial-perfusion; nitric-oxide; Pharmacology & Pharmacy; resistive vessel; unstable angina
For decades coronary macrovascular atherosclerosis has been considered the principal manifestation of coronary heart disease, with most of our effort dedicated to identifying and removal of coronary stenosis. However, growing body of literature indicates that coronary microcirculation also contributes substantially to the pathophysiology of cardiovascular disease. An understanding of mechanisms regulating microvascular function is of critical importance in understanding its role in disease, especially because these regulatory mechanisms vary substantially across species, vascular bed and due to comorbidities. Indeed, the most obvious consequence of coronary stenosis is that it may limit blood supply to the dependent myocardium to the point of causing ischaemia during exercise or even at rest. However, this flow limiting effect is not only due to the passive hydraulic effect of a narrowed conduit, but also to active responses in the coronary microcirculation triggered by the presence of an epicardial stenosis. To understand this problem it is important to review the inter-related mechanisms that regulate flow to the left ventricular wall and modulate transmural distribution of flow. These regulatory mechanisms operate hierarchically and are heterogeneously distributed along the coronary vascular tree. It is also important to discuss the effect of myocardial performance in modulating both blood flow demands and coronary resistance. Some of the interactions between coronary stenosis and microcirculation are transient, like those documented in acute coronary syndromes or during percutaneous interventions. However, microcirculatory remodeling may be triggered by a chronic coronary stenosis, leading to a sustained impairment of blood supply even after successful removal of the epicardial stenosis. A deeper understanding of these phenomena may explain paradoxical findings in patients undergoing coronary revascularization, particularly when functional tests are used in their assessment. These aspects are discussed in detail in this review.
Guarini G; Capozza P G; Huqi A; Morrone D; Chilian W M; Marzilli M
Current Pharmaceutical Design
2013
2013-04
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.2174/1381612811319130004" target="_blank" rel="noreferrer noopener">10.2174/1381612811319130004</a>