Intracellular Ca2+ Dysregulation in Coronary Smooth Muscle Is Similar in Coronary Disease of Humans and Ossabaw Miniature Swine

2021 ◽  
Author(s):  
Jill K. Badin ◽  
Caleb Eggenberger ◽  
Stacey Dineen Rodenbeck ◽  
Zubair A. Hashmi ◽  
I-wen Wang ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Coronary Disease ◽  
Miniature Swine ◽  
Coronary Smooth Muscle

scholarly journals Low-intensity interval exercise training attenuates coronary vascular dysfunction and preserves Ca2+-sensitive K+ current in miniature swine with LV hypertrophy

2011 ◽  
Vol 301 (4) ◽  
pp. H1687-H1694 ◽  
Author(s):  
Craig A. Emter ◽  
Darla L. Tharp ◽  
Jan R. Ivey ◽  
Venkataseshu K. Ganjam ◽  
Douglas K. Bowles
Keyword(s):  
Smooth Muscle ◽  
Exercise Training ◽  
Smooth Muscle Cell ◽  
Vascular Function ◽  
Vascular Dysfunction ◽  
Miniature Swine ◽  
Vascular Conductance ◽  
Coronary Smooth Muscle ◽  
Interval Exercise ◽  
Low Intensity

Coronary vascular dysfunction has been observed in several models of heart failure (HF). Recent evidence indicates that exercise training is beneficial for patients with HF, but the precise intensity and underlying mechanisms are unknown. Left ventricular (LV) hypertrophy can play a significant role in the development of HF; therefore, the purpose of this study was to assess the effects of low-intensity interval exercise training on coronary vascular function in sedentary (HF) and exercise trained (HF-TR) aortic-banded miniature swine displaying LV hypertrophy. Six months postsurgery, in vivo coronary vascular responses to endothelin-1 (ET-1) and adenosine were measured in the left anterior descending coronary artery. Baseline and maximal coronary vascular conductance were similar between all groups. ET-1-induced reductions in coronary vascular conductance ( P < 0.05) were greater in HF vs. sedentary control and HF-TR groups. Pretreatment with the ET type A (ETA) receptor blocker BQ-123 prevented ET-1 hypersensitivity in HF animals. Whole cell voltage clamp was used to characterize composite K+ currents ( IK+) in coronary smooth muscle cells. Raising internal Ca2+ from 200 to 500 nM increased Ca2+-sensitive K+ current in HF-TR and control, but not HF animals. In conclusion, an ETA-receptor-mediated hypersensitivity to ET-1, elevated resting LV wall tension, and decreased coronary smooth muscle cell Ca2+-sensitive IK+ was found in sedentary animals with LV hypertrophy. Low-intensity interval exercise training preserved normal coronary vascular function and smooth muscle cell Ca2+-sensitive IK+, illustrating a potential mechanism underlying coronary vascular dysfunction in a large-animal model of LV hypertrophy. Our results demonstrate the potential clinical impact of exercise on coronary vascular function in HF patients displaying pathological LV hypertrophy.

scholarly journals SIRT1 Inhibition Impairs Ca2+ Buffering in Coronary Smooth Muscle Cells of Ossabaw Miniature Swine

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
John Reed ◽  
Aish Thamba ◽  
John Strobel ◽  
James Byrd ◽  
Mouhamad Alloosh ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Coronary Artery ◽  
Smooth Muscle Cells ◽  
Single Cells ◽  
Muscle Cells ◽  
Atherogenic Diet ◽  
Miniature Swine ◽  
Rapid Phase ◽  
Coronary Smooth Muscle ◽  
Normal Chow

Background: SIRT1 is a deacetylase that has diverse roles in intracellular Ca2+ signaling, metabolism, and cardiovascular disease. SIRT1 increases sarco-endoplasmic reticulum Ca2+ ATPase (SERCA) activity that is essential to buffer the increase in Ca2+ induced by release from the sarcoplasmic reticulum (SR). Our lab has shown that metabolic syndrome (MetS) impairs SERCA activity in coronary smooth muscle cells and causes coronary artery disease in Ossabaw miniature swine. We hypothesized that  SIRT1 inhibition and MetS would impair Ca2+ buffering.   Methods: CRISPR/Cas9 methods delivered a leucine to proline point mutation in SIRT1 (SIRT1L100P) into the Ossabaw swine genome to compare to wild type (WT) and mimic the naturally occurring mutation in humans and decrease SIRT1 activity. Four treatment groups of juvenile swine were based on genotype and diet: WT Lean, SIRT1 Lean, WT MetS, and SIRT1 MetS. Lean swine were fed normal chow and MetS were fed a hypercaloric, atherogenic diet for 7 months. The left anterior descending coronary artery was harvested and enzymatically digested to obtain cells. Fluorescence microscopy measured the Ca2+ indicator fura-2 in single cells. The cells were exposed to 5 mM caffeine to maximally release stores of Ca2+ from the SR. Ca2+ buffering capacity of each cell was analyzed after the caffeine-induced peak increase to assess Ca2+ efflux and SERCA activity.   Results: MetS was confirmed by increased body weight, impaired glucose tolerance, hyperinsulinemia, and hypercholesterolemia. Coronary atherosclerosis was shown by angiography, intravascular ultrasound, and gross imaging. The rapid phase of Ca2+ buffering due to Ca2+ efflux was not affected by SIRT1 mutation or MetS. The slower phase of Ca2+ buffering due to SERCA activity was impaired only by SIRT1 mutation (p<0.0005), not by MetS.   Conclusion:  SIRT1 mutation alone inhibited SERCA buffering of Ca2+ in coronary smooth muscle. (Support: NIH T35HL110854, DK120240, DK09751.) 

scholarly journals Exercise training increases L-type calcium current density in coronary smooth muscle

1998 ◽  
Vol 275 (6) ◽  
pp. H2159-H2169 ◽  
Author(s):  
D. K. Bowles ◽  
Q. Hu ◽  
M. H. Laughlin ◽  
M. Sturek
Keyword(s):  
Smooth Muscle ◽  
Exercise Training ◽  
Current Density ◽  
Coronary Circulation ◽  
Cell Voltage ◽  
Inactivation Kinetics ◽  
Resistance Arteries ◽  
Miniature Swine ◽  
Coronary Smooth Muscle ◽  
Small Arteries

Exercise training produces numerous adaptations in the coronary circulation, including an increase in coronary tone, both in conduit and resistance arteries. On the basis of the importance of voltage-gated Ca2+ channels (VGCC) in regulation of vascular tone, we hypothesized that exercise training would increase VGCC current density in coronary smooth muscle. To test this hypothesis, VGCC current was compared in smooth muscle from conduit arteries (>1.0 mm), small arteries (200–250 μm), and large arterioles (75–150 μm) from endurance-trained (Ex) or sedentary miniature swine (Sed). After 16–20 wk of treadmill training, VGCC current was determined using whole cell voltage-clamp techniques. In both Ex and Sed, VGCC current density was inversely related to arterial diameter, i.e., large arterioles > small arteries > conduit arteries. Exercise training increased peak inward currents approximately twofold in smooth muscle from all arterial sizes compared with those from Sed (large arteriole, −12.52 ± 2.05 vs. −5.74 ± 0.99 pA/pF; small artery, −6.20 ± 0.97 vs. −3.18 ± 0.44 pA/pF; and conduit arteries, −4.22 ± 0.30 vs. −2.41 ± 0.55 pA/pF; 10 mM Ba2+ external). Dihydropyridine sensitivity, voltage dependence, and inactivation kinetics identified this Ca2+ current to be L-type current in all arterial sizes from both Sed and Ex. Furthermore, peak VGCC current density was correlated with treadmill endurance in all arterial sizes. We conclude that smooth muscle L-type Ca2+ current density is increased within the coronary arterial bed by endurance exercise training. This increased VGCC density may provide an important mechanistic link between functional and cellular adaptations in the coronary circulation to exercise training.

scholarly journals Metabolic Syndrome and SIRT1 Mutation Impair Ca2+ Channels in Coronary Smooth Muscle Cells of Ossabaw Miniature Swine

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Aish Thamba ◽  
John Reed ◽  
John S. Strobel ◽  
James Byrd ◽  
Mouhamad Alloosh ◽  
...  
Keyword(s):  
Coronary Artery Disease ◽  
Metabolic Syndrome ◽  
Smooth Muscle ◽  
Coronary Artery ◽  
Smooth Muscle Cells ◽  
Single Cells ◽  
Muscle Cells ◽  
Miniature Swine ◽  
Coronary Smooth Muscle ◽  
Artery Disease

Background: Changes in Ca2+ regulation have been implicated in various pathologies such as coronary artery disease and metabolic syndrome (MetS), thereby potentiating these diseases. Our lab has shown that MetS decreases voltage-gated Ca2+ channel (VGCC) activity and sarcoplasmic reticulum (SR) Ca2+ release in coronary smooth muscle cells and increases coronary artery disease in Ossabaw miniature swine. Furthermore, decreased SIRT1 enzyme function can impair Ca2+ signaling and increase coronary disease and MetS. We hypothesized that impaired SIRT1 and MetS would decrease VGCC function and SR calcium store. Methods: CRISPR/Cas9 methods delivered a leucine to proline point mutation in SIRT1 (SIRT1L100P) into the Ossabaw swine genome to compare to wild type (WT), mimicking the naturally occurring mutation in humans which decreases SIRT1 activity. Four treatment groups of juvenile swine were based on genotype and diet: WT Lean, SIRT1 Lean, WT MetS, and SIRT1 MetS. Lean swine were fed normal chow and MetS were fed a hypercaloric, atherogenic diet for 7 months. The left anterior descending coronary artery was harvested and enzymatically digested to obtain cells. Fluorescence microscopy measured the Ca2+ indicator fura-2 in single cells. Depolarization of cells with perfusion of 80 mM K+ was used to elicit Ca2+ influx through VGCC.  Caffeine (5 mM) exposure activated the Ca2+ release channel (ryanodine receptor) on the SR. Results: MetS was confirmed by increased body weight, impaired glucose tolerance, hyperinsulinemia, and hypercholesterolemia. Coronary atherosclerosis was shown by angiography, intravascular ultrasound, and gross imaging. A two-way analysis of variance revealed statistically significant overall effects of genotype (p=0.02), diet (p<0.0001), and an interaction (p<0.0001) between these variables to decrease VGCC function. In contrast, no effect was observed on SR Ca2+ release. Conclusion and Potential Impact: SIRT1 inhibition and MetS decreased VGCC function independently, but not additively or synergistically. (Support: NIH T35HL110854, DK120240, DK09751.)

scholarly journals Altered calcium sensitivity contributes to enhanced contractility of collateral-dependent coronary arteries

2004 ◽  
Vol 97 (1) ◽  
pp. 310-316 ◽  
Author(s):  
Cristine L. Heaps ◽  
Janet L. Parker ◽  
Michael Sturek ◽  
Douglas K. Bowles
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Coronary Arteries ◽  
Calcium Sensitivity ◽  
Miniature Swine ◽  
Luminal Diameter ◽  
Coronary Smooth Muscle ◽  
Fura 2 ◽  
Channel Current ◽  
Chronic Occlusion

Coronary arteries distal to chronic occlusion exhibit enhanced vasoconstriction and impaired relaxation compared with nonoccluded arteries. In this study, we tested the hypotheses that an increase in peak Ca2+ channel current density and/or increased Ca2+ sensitivity contributes to altered contractility in collateral-dependent coronary arteries. Ameroid occluders were surgically placed around the proximal left circumflex coronary artery (LCX) of female miniature swine. Segments of epicardial arteries (∼1 mm luminal diameter) were isolated from the LCX and nonoccluded left anterior descending (LAD) arteries 24 wk after Ameroid placement. Contractile responses to depolarization (10–100 mM KCl) were significantly enhanced in LCX compared with size-matched LAD arterial rings [concentration of KCl causing 50% of the maximal contractile response (EC50); LAD = 41.7 ± 2.3, LCX = 34.3 ± 2.7 mM]. However, peak Ca2+ channel current was not altered in isolated smooth muscle cells from LCX compared with LAD (−5.29 ± 0.42 vs. −5.68 ± 0.55 pA/pF, respectively). Furthermore, whereas half-maximal activation of Ca2+ channel current occurred at nearly the same membrane potential in LAD and LCX, half-maximal inactivation was shifted to a more positive membrane potential in LCX cells. Simultaneous measures of contractile tension and intracellular free Ca2+ (fura 2) levels in arterial rings revealed that significantly more tension was produced per unit change in fura 2 ratio in LCX compared with LAD in response to KCl but not during receptor-agonist stimulation with endothelin-1. Taken together, our data indicate that coronary arteries distal to chronic occlusion display increased Ca2+ sensitivity in response to high KCl-induced depolarization, independent of changes in whole cell peak Ca2+ channel current. Unaltered Ca2+ sensitivity in endothelin-stimulated arteries suggests more than one mechanism regulating Ca2+ sensitization in coronary smooth muscle.

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