507 Late-Breaking: Heat Stress and Mitoq Supplementation Impact Skeletal Muscle Mitochondrial Capacities in Pigs

Abstract Heat stress can negatively impact pig health and performance but the effects of heat stress on skeletal muscle mitochondrial function are largely unknown. We hypothesized that mitochondrial function and capacity would be impaired in heat stressed (HS) compared to thermoneutral (TN) pigs but mitochondrially-targeted coenzyme Q (MitoQ) supplementation would rescue the impairment. Oxidative portions of the semitendinosus muscle were evaluated from TN and HS gilts receiving no supplementation (CON) or MitoQ for 2 d prior to and during the 24h environmental heat treatment (n = 8 per group). Mitochondrial oxidative phosphorylation (P) and electron transfer (E) capacities were determined via high resolution respirometry and mitochondrial volume density and function were quantified by citrate synthase (CS) and cytochrome c oxidase activities, respectively. Data were analyzed using linear models in SAS v9.4 with fixed effects of heat, MitoQ treatment (trt), and heat×trt interaction. There were trends for the interaction of trt and heat (P≤0.1) on integrative (per mg tissue) and intrinsic (relative to CS) P with complexes I and II (PCI+II), maximum noncoupled E (ECI+II), and E with complex II only (ECII), in which all measures were greater in HS-MitoQ than TN-MitoQ (P≤0.03), but measures did not differ due to HS in CON pigs. The contribution of leak to total E (flux control ratio, FCRLeak) was lesser in HS-MitoQ than HS-CON, TN-CON, and TN-MitoQ (P≤0.02). The FCRPCI was greater (P≤0.05) while the FCRPCI+II was lesser (P=0.01) in TN compared to HS pigs. Finally, the FCRPCI+II was greater (P=0.02) while the FCRECII tended to be lesser (P=0.09) for CON than MitoQ pigs. Neither mitochondrial volume density nor function were affected by HS or MitoQ supplementation. In total, these data indicate improved mitochondrial capacities following heat stress in pigs receiving MitoQ but no difference in mitochondrial capacities in unsupplemented, HS pigs.

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241 Skeletal Muscle Mitochondrial Capacities Are Impacted by Breed and Temperament in Young Angus and Brahman Steers

Journal of Animal Science ◽

10.1093/jas/skab235.231 ◽

2021 ◽

Vol 99 (Supplement_3) ◽

pp. 127-127

Author(s):

Chloey P Guy ◽

Lauren T Wesolowski ◽

Audrey L Earnhardt ◽

Dustin Law ◽

Don A Neuendorff ◽

...

Keyword(s):

Skeletal Muscle ◽

Fixed Effects ◽

Linear Models ◽

Citrate Synthase ◽

Volume Density ◽

Skeletal Muscle Mitochondria ◽

Mitochondrial Volume ◽

Mitochondrial Volume Density ◽

Brahman Steers ◽

The Impact

Abstract Temperament impacts skeletal muscle mitochondria in Brahman heifers, but this has not been investigated in steers or between cattle breeds. We hypothesized mitochondrial measures would be greater in Angus than Brahman, temperamental than calm steers, and the trapezius (TRAP) than the longissimus thoracis (LT) muscle. Samples from calm (n = 13 per breed), intermediate (n = 12 per breed), and temperamental (n=13 per breed) Angus and Brahman steers (mean±SD 10.0±0.8 mo) were evaluated for mitochondrial enzyme activities via colorimetry. Calm and temperamental LT samples were evaluated for oxidative phosphorylation (P) and electron transfer (E) capacities by high-resolution respirometry. Data were analyzed using linear models with fixed effects of breed, muscle, temperament, and all interactions. Brahman tended to have greater mitochondrial volume density (citrate synthase activity; CS) than Angus (P = 0.08), while intrinsic (relative to CS) mitochondrial function (cytochrome c oxidase activity) was greater in Angus than Brahman (P = 0.001) and greater in TRAP than LT (P = 0.008). Angus exhibited greater integrative (per mg tissue) and intrinsic P with complex I (PCI), P with complexes I+II (PCI+II), maximum noncoupled E, and E with complex II (ECII; P ≤ 0.04) and tended to have greater intrinsic leak (P = 0.1) than Brahman. Contribution of PCI to total E was greater in Angus than Brahman (P = 0.01), while contribution of ECII to total E was greater in Brahman than Angus (P = 0.05). A trend for the interaction of breed and temperament (P = 0.07) indicated calm Angus had the greatest intrinsic ECII (P ≤ 0.03) while intrinsic ECII was similar between temperamental Angus and calm and temperamental Brahman. Integrative PCI+II and ECII, and the contribution of PCI and PCI+II to overall E tended to be greater in temperamental than calm steers (P ≤ 0.09), while intrinsic ECII tended to be greater in calm than temperamental steers (P = 0.07). The impact of these mitochondrial differences on meat quality measures remains to be determined.

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108 President Oral Presentation Pick: Select skeletal muscle mitochondrial measures in Thoroughbred weanlings are related to race earnings and sire

Journal of Animal Science ◽

10.1093/jas/skaa278.155 ◽

2020 ◽

Vol 98 (Supplement_4) ◽

pp. 85-85

Author(s):

Chloey P Guy ◽

Christine M Latham ◽

Randi N Owen ◽

Ashley L Fowler ◽

Sarah H White-Springer

Keyword(s):

Skeletal Muscle ◽

Complex I ◽

Fixed Effects ◽

Linear Models ◽

Citrate Synthase ◽

Pearson Correlation ◽

Gluteus Medius ◽

Volume Density ◽

Complex Ii ◽

And Training

Abstract Quantifiable, cellular differences of individuals are not widely used in breeding and training decisions in the equine industry. Our objective was to determine if mitochondrial parameters in weanling Thoroughbreds were related to sire or lifetime race earnings. We hypothesized that weanling skeletal muscle mitochondrial capacity would be positively correlated with race earnings. Gluteus medius muscle samples were collected from racing-bred Thoroughbred weanlings (n = 139; mean ± SD; 6.0 ± 0.4 mo) from 40 different sires over 3 years at 5 different farms and evaluated for mitochondrial volume density (citrate synthase activity; CS) and function (cytochrome c oxidase activity) by colorimetry, and oxidative (P) and electron transport system (E) capacities by high resolution respirometry; two- and three-year-old race earnings were available for a subset of 13 horses. Data were analyzed using mixed linear models with sire, sex, year of collection, and farm as fixed effects. Correlations between lifetime race earnings and mitochondrial measures were determined using Pearson Correlation Statistics. A main effect of sire was observed for weanling intrinsic (relative to CS activity) P with complex I substrates (P = 0.04) and the contribution of mitochondrial leak to O2 consumption (FCRL; P = 0.04). A trend was observed for the effect of sire on intrinsic mitochondrial leak (P = 0.09). Race earnings were positively correlated with integrated (relative to mg protein) leak (r = 0.7684, P = 0.009) and FCRL (r = 0.7035; P = 0.02). A trend for a negative correlation between E with complex II substrates and race earnings was also observed (r = -0.4775, P = 0.09), No other measures were influenced by sire, nor were correlated with race earnings. Our previous work has indicated a preferential use of complex I in breeds bred for short-duration racing (Thoroughbreds) compared to distance racing breeds (Standardbreds) that relied more heavily on complex II. Mitochondrial measures in weanlings may be utilized to inform future breeding and training decisions in horses.

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145 President Oral Presentation Pick: Prenatal stress increases skeletal muscle mitochondrial volume density and function in yearling Brahman calves

Journal of Animal Science ◽

10.1093/jas/skaa278.219 ◽

2020 ◽

Vol 98 (Supplement_4) ◽

pp. 120-121

Author(s):

Chloey P Guy ◽

Catherine L Wellman ◽

David G Riley ◽

Charles R Long ◽

Ron D Randel ◽

...

Keyword(s):

Oxidative Stress ◽

Creatine Kinase ◽

Muscle Damage ◽

Prenatal Stress ◽

Citrate Synthase ◽

Volume Density ◽

Assembly Factor ◽

Mitochondrial Volume ◽

Mitochondrial Volume Density ◽

And Function

Abstract We previously determined that prenatal stress (PNS) differentially affected methylation of DNA from leukocytes of 28-d-old calves. Specifically, COX14 (cytochrome c oxidase (COX) assembly factor) and CKMT1B (mitochondrial creatine kinase U-type) were hypomethylated and COA5 (COX assembly factor 5), COX5A (COX subunit 5A), NRF1 (nuclear respiratory factor 1), and GSST1 (glutathione S-transferase theta-1) were hypermethylated in PNS compared to non-PNS calves (P ≤ 0.05). Our current objective was to test the hypothesis that PNS exhibit impaired mitochondrial function and greater oxidative stress than non-PNS calves. Blood and longissimus dorsi muscle samples were collected from yearling Brahman calves whose mothers were stressed by 2 h transportation at 60, 80, 100, 120, and 140 days of gestation (PNS; 8 bulls, 6 heifers) and non-PNS calves (4 bulls, 6 heifers). Serum was evaluated for the stress hormone, cortisol, and muscle damage marker, creatine kinase; muscle was analyzed for mitochondrial volume density and function by citrate synthase (CS) and COX activities, respectively, concentration of malondialdehyde, a lipid peroxidation marker, and activity of the antioxidant, superoxide dismutase (SOD). Data were analyzed using mixed linear models with treatment and sex as fixed effects. Serum cortisol was numerically higher in PNS than non-PNS calves but was not statistically different. Muscle CS and COX activities relative to protein were greater in PNS than non-PNS calves (P ≤ 0.03), but COX relative to CS activity was similar between groups. Activity of COX was greater in bulls than heifers (P = 0.03), but no other measure was affected by sex. All other measures were unaffected by PNS. Prenatal stress did not affect markers of muscle damage and oxidative stress in yearling Brahman calves at rest but mitochondrial volume density and function were greater in PNS calves. Acute stressors induce oxidative stress, so implications of differences in mitochondria in PNS calves following a stressor should be investigated.

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Exercise training increases skeletal muscle mitochondrial volume density by enlargement of existing mitochondria and not de novo biogenesis

Acta Physiologica ◽

10.1111/apha.12905 ◽

2017 ◽

Vol 222 (1) ◽

pp. e12905 ◽

Cited By ~ 44

Author(s):

A.-K. Meinild Lundby ◽

R. A. Jacobs ◽

S. Gehrig ◽

J. de Leur ◽

M. Hauser ◽

...

Keyword(s):

Skeletal Muscle ◽

Exercise Training ◽

De Novo ◽

Volume Density ◽

Mitochondrial Volume ◽

Mitochondrial Volume Density

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MITOCHONDRIAL VOLUME DENSITY CORRELATES WITH FATIGUABILITY OF INDIVIDUAL SINGLE SKELETAL MUSCLE FIBERS

Medicine & Science in Sports & Exercise ◽

10.1097/00005768-200205001-01473 ◽

2002 ◽

Vol 34 (5) ◽

pp. S263

Author(s):

C M. Stary ◽

O Matthieu-Costello ◽

M C. Hogan

Keyword(s):

Skeletal Muscle ◽

Muscle Fibers ◽

Volume Density ◽

Skeletal Muscle Fibers ◽

Mitochondrial Volume ◽

Mitochondrial Volume Density

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Mammals: an allometric study of metabolism at tissue and mitochondrial level

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1985.248.4.r415 ◽

1985 ◽

Vol 248 (4) ◽

pp. R415-R421 ◽

Cited By ~ 14

Author(s):

P. L. Else ◽

A. J. Hulbert

Keyword(s):

Skeletal Muscle ◽

Surface Area ◽

Mitochondrial Membrane ◽

Membrane Surface ◽

Standard Metabolic Rate ◽

Volume Density ◽

Allometric Equation ◽

Membrane Surface Area ◽

Mitochondrial Volume ◽

Mitochondrial Volume Density

Body composition, mitochondrial volume density, and mitochondrial membrane surface area were measured in six species of mammals representing a 100-fold weight range (18-2,067 g). The mammals examined included three eutherian species, two marsupial, and one monotreme species. The tissues examined were liver, kidney, brain, lung, heart, and skeletal muscle (gastrocnemius). Allometric equations were derived for tissue weight, and the allometric exponents ranged from 0.69 (brain) to 1.01 (skeletal muscle). Allometric relationships for mitochondrial membrane surface area were also determined both per milliliter tissue and per total tissue. Small mammals had a higher mitochondrial membrane surface area per milliliter tissue than large mammals in all tissues examined. These differences were significant in liver, kidney, brain, and heart. Total mitochondrial membrane surface area per tissue had allometric exponents ranging from 0.55 (kidney) to 0.78 (skeletal muscle). When total mitochondrial membrane surface area was summated for the major internal organs examined (liver, kidney, heart, and brain), the allometric equation was mitochondrial membrane surface area (m2) = 3.04 body wt0.59 (g). This was similar to the exponent of standard metabolic rate against body weight in the species examined (i.e., 0.62). The inclusion of skeletal muscle and lung into the summated mitochondrial membrane surface area increased the exponent to 0.76. This is compared with the relationship between maximal O2 consumption and body size in mammals.

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