Sedentary Dams Research Articles

Maternal exercise preserves offspring cardiovascular health via oxidative regulation of the ryanodine receptor

ObjectiveThe intrauterine environment during pregnancy is a critical factor in the development of obesity, diabetes, and cardiovascular disease in offspring. Maternal exercise prevents the detrimental effects of a maternal high fat diet on the metabolic health in adult offspring, but the effects of maternal exercise on offspring cardiovascular health have not been thoroughly investigated. MethodsTo determine the effects of maternal exercise on offspring cardiovascular health, female mice were fed a chow (C; 21% kcal from fat) or high-fat (H; 60% kcal from fat) diet and further subdivided into sedentary (CS, HS) or wheel exercised (CW, HW) prior to pregnancy and throughout gestation. Offspring were maintained in a sedentary state and chow-fed throughout 52 weeks of age and subjected to serial echocardiography and cardiomyocyte isolation for functional and mechanistic studies. ResultsHigh-fat fed sedentary dams (HS) produced female offspring with reduced ejection fraction (EF) compared to offspring from chow-fed dams (CS), but EF was preserved in offspring from high-fat fed exercised dams (HW) throughout 52 weeks of age. Cardiomyocytes from HW female offspring had increased kinetics, calcium cycling, and respiration compared to CS and HS offspring. HS offspring had increased oxidation of the RyR2 in cardiomyocytes coupled with increased baseline sarcomere length, resulting in RyR2 overactivity, which was negated in female HW offspring. ConclusionsThese data suggest a role for maternal exercise to protect against the detrimental effects of a maternal high-fat diet on female offspring cardiac health. Maternal exercise improved female offspring cardiomyocyte contraction, calcium cycling, respiration, RyR2 oxidation, and RyR2 activity. These data present an important, translatable role for maternal exercise to preserve cardiac health of female offspring and provide insight on mechanisms to prevent the transmission of cardiovascular diseases to subsequent generations.

Maternal Exercise Protects Male Offspring from Maternal Diet Programmed Non-Alcoholic Fatty Liver Disease Progression.

Maternal obesity programs risk for development of non-alcoholic fatty liver disease (NAFLD) in offspring. Maternal exercise is a potential intervention to prevent developmentally programmed phenotypes. We hypothesized that maternal exercise would protect from progression of NAFLD in offspring previously exposed to maternal obesogenic diet. Female mice were fed chow (CON) or HFFC and bred with lean males. A subset had an exercise wheel introduced 4 weeks after starting diet to allow for voluntary exercise. The offspring were weaned to HFFC diet for 7 weeks to induce NAFLD. Serum, adipose, and liver tissue were collected for metabolic, histologic, and gene expression analyses. Cecal contents were collected for 16S sequencing. Global metabolomics was performed on liver. Female mice fed HFFC diet had increased body weight prior to adding an exercise wheel. Female mice fed HFFC diet had an increase in exercise distance relative to CON during the pre-conception period. Exercise distance was similar between groups during pregnancy and lactation. CON-Active and HFFC-Active offspring exhibited decreased inflammation compared to offspring from sedentary dams. Fibrosis increased in offspring from HFFC-sedentary dams compared to CON-sedentary. Offspring from exercised HFFC dams exhibited less fibrosis than offspring from sedentary HFFC dams. While maternal diet significantly affected the microbiome of offspring, the effect of maternal exercise was minimal. Metabolomics analysis revealed shifts in multiple metabolites including several involved in bile acid, one-carbon, histidine, and acylcarnitine metabolism. This study provides pre-clinical evidence that maternal exercise is a potential approach to prevent developmentally programmed liver disease progression in offspring.

700-P: Mechanism for the Beneficial Effects of Maternal Exercise to Improve Offspring Metabolic Health

Poor maternal diet and obesity increase the risk of obesity and type 2 diabetes in offspring, fueling the worldwide epidemic of these diseases. Recent animal studies have shown that maternal exercise (MatEx) improves the metabolic phenotype of offspring in adulthood, including improved glucose tolerance and liver function. Here, we determined the molecular mechanisms responsible for these critical effects of MatEx. Female mice were fed a chow or high fat diet and housed in cages with (Trained) or without (Sedentary) running wheels for 2 wks prior to breeding and during gestation. Offspring were sedentary and chow-fed. MatEx improved glucose tolerance and liver function in adult offspring. Beginning at embryonic day 13.5, MatEx increased expression of TCA cycle and fatty acid oxidation genes in offspring liver, and increased DNA demethylation at promoters of these hepatic genes. Next, we identified a novel MatEx-induced AMPK/isocitrate dehydrogenase/αketoglutarate/Tet axis in offspring liver controlling DNA demethylation. Primary hepatoblasts treated with serum from trained dams, but not sedentary dams or trained non-pregnant females stimulated this pathway, suggesting the effects of MatEx on offspring stem from a placenta-derived serum factor(s). LC-MS/MS of serum and RNAseq of placenta from trained dams identified this factor as superoxide dismutase 3 (Sod3), and recombinant SOD3 treatment of hepatoblasts increased AMPK-Tet signaling and hepatic gene expression. The effects of MatEx to increase liver AMPK-Tet signal, alter liver DNA methylation and gene expression, and improve offspring glucose tolerance in vivo were ablated in placenta-specific Sod3 KO mice. Finally, SOD3 was increased in serum and placenta from highly physically active pregnant women. Sod3 is an exercise-induced, placenta-derived protein that improves glucose homeostasis via epigenetic changes in offspring liver, defining a novel paradigm for the beneficial effects of exercise on metabolic health. Disclosure J. Kusuyama: None. A.B. Wagner: None. R.H. Conlin: None. N.S. Makarewicz: None. M. Møller: None. E.M. Miele: None. R. Middelbeek: None. N. Jessen: None. P.G. Ovesen: None. M.F. Hirshman: Stock/Shareholder; Self; Abbott Laboratories, AbbVie Inc., Amgen, Colgate-Palmolive, Eli Lilly and Company, Medtronic. K.B. Adamo: None. E.N. Grayck: None. L.J. Goodyear: None. Funding National Institutes of Health (DK101043)

1395-P: Maternal Exercise during Pregnancy Affects Offspring Adiposity through One Carbon Metabolism Cycle

Maternal obesity during pregnancy can adversely affect adult offspring adiposity and insulin resistance. The goal of this study was to determine if maternal exercise mitigates the adverse effects of maternal obesity on offspring health. Female (C57BL/6NJ) mice were fed from weaning a control diet (10%kcal fat; MC n=18) or western diet (45% kcal fat; MW n=15) to induce excess adiposity. After 13 weeks, the mice were bred and maintained on the diets, with (E) and without (S) access to a running wheel (exercise), throughout pregnancy and lactation. Offspring were weaned onto the control diet and fed for 13 weeks; male offspring were studied. Offspring from MWE dams had greater (p<0.05) retroperitoneal and mesenteric adipose tissue than offspring from MWS dams. This was not observed in offspring from dams fed the control diet. Offspring from exercised dams had lower glucose-stimulated insulin secretion compared to those from sedentary dams, independent of maternal diet. No differences in glucose and insulin tolerance were observed. One carbon metabolism is required for several physiological processes including DNA synthesis, amino and lipid metabolism, and the generation of methyl groups. Disturbances in one carbon metabolism occur in obesity. We hypothesized that maternal exercise mitigates the adverse effects of maternal obesity on offspring adiposity through changes in one carbon metabolism. MCE offspring had lower serum total homocysteine (6.3μmol/L) compared to MCS offspring (9.4μmol/L). This was not observed in the offspring from western diet-fed dams. Offspring from western diet-fed dams had higher hepatic methylenetetrahydrofolate reductase (Mthfr) mRNA expression compared to offspring from control diet-fed dams. Offspring from dams that exercised also had higher hepatic Mthfr mRNA; the highest expression was observed in MWE offspring. The findings from this study suggest that one carbon metabolism may play a role in developmental programing of offspring adiposity. Disclosure N. Boonpattrawong: None. A. Mehran: None. I. Laher: None. A.M. Devlin: None. Funding Canadian Institutes of Health Research

Swimming exercise before and during pregnancy: Promising preventive approach to impact offspring´s health

Several environmental factors affect child development, such as the intrauterine environment during the embryonic and fetal development and early postnatal environment provided by maternal behavior. Although mechanistic effects of maternal exercise on offspring health improvement are not yet completely understood, the number of reports published demonstrating the positive influence of maternal exercise have increase. Herein, we addressed issues related to early postnatal environment provided by maternal behavior and early developmental physical landmarks, sensorimotor reflexes, and motor movements ontogeny. In brief, adult female rats underwent involuntary swimming exercise, in a moderated intensity, one week before mating and throughout pregnancy, 30 min a day, 5 days a week. Maternal exercised dams have unchanged gestational outcomes compared to sedentary dams. We found no differences concerning the frequency of pup-directed behavior displayed by dams. However, sedentary dams displayed a poorer pattern of maternal care quality during dark cycle than exercised dams. Physical landmarks and sensorimotor reflexes development of female and male littermates did not differ between maternal groups. Developmental motor parameters such as immobility, lateral head movements, head elevation, pivoting, rearing with forelimb support and crawling frequencies did not differ between groups. Pups born to exercised dams presented higher frequency of walking and rearing on the hind legs. These data suggest that female and male littermates of exercised group present a high frequency of exploratory behavior over sedentary littermates. Taken together, the present findings reinforce that maternal exercise throughout pregnancy represent a window of opportunity to improve offspring’s postnatal health.

Brain Metabolism Alterations Induced by Pregnancy Swimming Decreases Neurological Impairments Following Neonatal Hypoxia-Ischemia in Very Immature Rats.

Introduction: Prematurity, through brain injury and altered development is a major cause of neurological impairments and can result in motor, cognitive and behavioral deficits later in life. Presently, there are no well-established effective therapies for preterm brain injury and the search for new strategies is needed. Intra-uterine environment plays a decisive role in brain maturation and interventions using the gestational window have been shown to influence long-term health in the offspring. In this study, we investigated whether pregnancy swimming can prevent the neurochemical metabolic alterations and damage that result from postnatal hypoxic-ischemic brain injury (HI) in very immature rats.Methods: Female pregnant Wistar rats were divided into swimming (SW) or sedentary (SE) groups. Following a period of adaptation before mating, swimming was performed during the entire gestation. At postnatal day (PND3), rat pups from SW and SE dams had right common carotid artery occluded, followed by systemic hypoxia. At PND4 (24 h after HI), the early neurochemical profile was measured by 1H-magnetic resonance spectroscopy. Astrogliosis, apoptosis and neurotrophins protein expression were assessed in the cortex and hippocampus. From PND45, behavioral testing was performed. Diffusion tensor imaging and neurite orientation dispersion and density imaging were used to evaluate brain microstructure and the levels of proteins were quantified.Results: Pregnancy swimming was able to prevent early metabolic changes induced by HI preserving the energetic balance, decreasing apoptotic cell death and astrogliosis as well as maintaining the levels of neurotrophins. At adult age, swimming preserved brain microstructure and improved the performance in the behavioral tests.Conclusion: Our study points out that swimming during gestation in rats could prevent prematurity related brain damage in progeny with high translational potential and possibly interesting cost-benefits.HIGHLIGHTS - Prematurity is a major cause of neurodevelopmental impairments;- Swimming during pregnancy reduces brain damage after HI injury;- Pregnancy is an important but underestimated preventive window.

Aerobic Exercise Preconception and During Pregnancy Enhances Oxidative Capacity in the Hindlimb Muscles of Mice Offspring.

Liu, J, Lee, I, Feng, H-Z, Galen, SS, Hüttemann, PP, Perkins, GA, Jin, J-P, Hüttemann, M, and Malek, MH. Aerobic exercise preconception and during pregnancy enhances oxidative capacity in the hindlimb muscles of mice offspring. J Strength Cond Res 32(5): 1391-1403, 2018-Little is known about the effect of maternal exercise on offspring skeletal muscle health. The purpose of this study, therefore, was to determine whether maternal exercise (preconception and during pregnancy) alters offspring skeletal muscle capillarity and mitochondrial biogenesis. We hypothesized that offspring from exercised dams would have higher capillarity and mitochondrial density in the hindlimb muscles compared with offspring from sedentary dams. Female mice in the exercise condition had access to a running wheel in their individual cage 30 days before mating and throughout pregnancy, whereas the sedentary group did not have access to the running wheel before mating and during pregnancy. Male offspring from both groups were killed when they were 2 months old, and their tissues were analyzed. The results indicated no significant (p > 0.05) mean differences for capillarity density, capillarity-to-fiber ratio, or regulators of angiogenesis such as VEGF-A and TSP-1. Compared with offspring from sedentary dams, however, offspring from exercised dams had an increase in protein expression of myosin heavy chain type I (MHC I) (∼134%; p = 0.009), but no change in MHC II. For mitochondrial morphology, we found significant (all p-values ≤ 0.0124) increases in mitochondrial volume density (∼55%) and length (∼18%) as well as mitochondria per unit area (∼19%). For mitochondrial enzymes, there were also significant (all p-values ≤ 0.0058) increases in basal citrate synthase (∼79%) and cytochrome c oxidase activity (∼67%) in the nonoxidative muscle fibers as well as increases in basal (ATP) (∼52%). Last, there were also significant mean differences in protein expression for regulators (FIS1, Lon protease, and TFAM) of mitochondrial biogenesis. These findings suggest that maternal exercise before and during pregnancy enhances offspring skeletal muscle mitochondria functionality, but not capillarity.

Maternal Exercise Improves Glucose Tolerance in Female Offspring.

Poor maternal diet can lead to metabolic disease in offspring, whereas maternal exercise may have beneficial effects on offspring health. In this study, we determined ifmaternal exercise could reverse the detrimental effects of maternal high-fat feeding on offspring metabolism of female mice. C57BL/6 female mice were fed a chow (21%) or high-fat (60%) diet and further divided by housing in static cages or cages with running wheels for 2 weeks prior to breeding and throughout gestation. Females were bred with chow-fed sedentary C57BL/6 males. High fat–fed sedentary dams produced female offspring with impaired glucose tolerance compared with offspring of chow-fed dams throughout their first year of life, an effect not present in the offspring from high fat–fed dams that had trained. Offspring from high fat–fed trained dams had normalized glucose tolerance, decreased fasting insulin, and decreased adiposity. Liver metabolic function, measured by hepatic glucose production in isolated hepatocytes, hyperinsulinemic-euglycemic clamps, liver triglyceride content, and liver enzyme expression, was enhanced in offspring from trained dams. In conclusion, maternal exercise negates the detrimental effects of a maternal high-fat diet on glucose tolerance and hepatocyte glucose metabolism in female offspring. The ability of maternal exercise to improve the metabolic health of female offspring is important, as this intervention could combat the transmission of obesity and diabetes to subsequent generations.

Cardiac Adaptation To Exercise During Pregnancy

The extracellular composition and cardiac capillary density determine physiological from pathological cardiac hypertrophy. A number of studies demonstrate that exercise training does not increase fibrosis, whereas exercise training does increase capillary density and antioxidant capacity. However, whether exercise during pregnancy in previous sedentary dams could modify these parameters has not been investigated. METHODS AND RESULTS: 10 week old C57Bl/6 female mice were divided into non-pregnant diestrus control (C), late pregnancy (LP), and exercise during pregnancy (EX+LP). The EX+LP group was subjected to voluntary wheel running from gestation day 1 to 17. The pattern of running activity was high in early pregnancy and gradually decreased to low levels after mid-pregnancy. We found that both LP and EX+LP groups significantly increased heart mass normalized to tibial length (HW/TL). However, there were no differences in cardiac hypertrophy between LP and EX+LP. Next, we measured extracellular remodeling genes, angiogenic factors, and antioxidant related genes by quantitative real time PCR. mRNA levels of collagens, including Col1a1, Col3a1, and Col8a1, and connective tissue growth factor (Ctgf) were not altered in both LP and EX+LP groups compared to C. In addition, mRNA levels of angiogenic factors, including PGC-1α (Pgc1a), vascular endothelial growth factor a (Vegfa), angiogpietin-1 (Angpt1), Angpt2, fibroblast growth factor 2 (Fgf2), and platelet-derived growth factor alpha (Pdgfa) were not altered as well as antioxidant enzymes in both LP and EX+LP groups compared to C. CONCLUSION: Our results suggest that maternal exercise during pregnancy does not further increase pregnancy-induced cardiac hypertrophy. However, exercise during pregnancy may not be sufficient to activate the genes regulating angiogenesis and the antioxidant defense system.

Maternal exercise during pregnancy reduces risk of mammary tumorigenesis in rat offspring

Breast cancer is the most common cancer among women. Emerging research indicates that modifying lifestyle factors during pregnancy may convey long-term health benefits to offspring. This study was designed to determine whether maternal exercise during pregnancy leads to reduced mammary tumorigenesis in female offspring. Pregnant rats were randomly assigned to exercised and sedentary groups, with the exercised group having free access to a running wheel and the sedentary group housed with a locked wheel during pregnancy. Female pups from exercised or sedentary dams were weaned at 21 days of age and fed a high fat diet without access to a running wheel. At 6 weeks, all pups were injected with the carcinogen N-methyl-N-nitrosourea. Mammary tumor development in all pups was monitored for 15 weeks. Pups from exercised dams had a substantially lower tumor incidence (42.9%) compared with pups from sedentary dams (100%). Neither tumor latency nor histological grade differed between the two groups. These data are the first to demonstrate that exercise during pregnancy potentiates reduced tumorigenesis in offspring. This study provides an important foundation towards developing more effective modes of behavior modification for cancer prevention.

Exercise before and during pregnancy prevents the deleterious effects of maternal high-fat feeding on metabolic health of male offspring.

The intrauterine environment during pregnancy is a critical factor in the development of diabetes and obesity in offspring. To determine the effects of maternal exercise during pregnancy on the metabolic health of offspring, 6-week-old C57BL/6 virgin female mice were fed a chow (21%) or high-fat (60%) diet and divided into four subgroups: trained (housed with running wheels for 2 weeks preconception and during gestation), prepregnancy trained (housed with running wheels for 2 weeks preconception), gestation trained (housed with running wheels during gestation), or sedentary (static cages). Male offspring were chow fed, sedentary, and studied at 8, 12, 24, 36, and 52 weeks of age. Offspring from chow-fed dams that trained both before and during gestation had improved glucose tolerance beginning at 8 weeks of age and continuing throughout the 1st year of life, and at 52 weeks of age had significantly lower serum insulin concentrations and percent body fat compared with all other groups. High-fat feeding of sedentary dams resulted in impaired glucose tolerance, increased serum insulin concentrations, and increased percent body fat in offspring. Remarkably, maternal exercise before and during gestation ameliorated the detrimental effect of a maternal high-fat diet on the metabolic profile of offspring. Exercise before and during pregnancy may be a critical component for combating the increasing rates of diabetes and obesity.

Maternal exercise during pregnancy reduces risk of mammary tumorigenesis in rat offspring (886.1)

Breast cancer is the most common cancer among women. Emerging research indicates that modifying lifestyle factors during pregnancy may convey long‐term health benefits to offspring. This study was designed to determine whether maternal exercise during pregnancy leads to reduced mammary tumorigenesis in female offspring. Pregnant rats were randomly assigned to exercised and sedentary groups, with the exercised group having free access to a running wheel and the sedentary group housed with a locked wheel during pregnancy. Female pups from exercised or sedentary dams were weaned at 21 days of age and fed a high fat diet without access to a running wheel. At 6 weeks, all pups were injected with the carcinogen N‐methyl‐N‐nitrosourea (MNU). Mammary tumor development in all pups was monitored for 15 weeks. Pups from exercised dams had a substantially lower tumor incidence (42.9%) compared to pups from sedentary dams (100%). Of the pups with tumors, the pups from exercised dams had a higher tumor frequency (1.7±0.4 tumors/rat) than pups from sedentary dams (1.2±0.2 tumors/rat). Neither tumor latency nor histological grade differed between the two groups. These data are the first to demonstrate that exercise during pregnancy potentiates reduced tumorigenesis in offspring. This study provides an important foundation towards developing more effective modes of behavior modification for cancer prevention.Grant Funding Source: Supported by NIH R25CA128770 and ICTSI NIH/NCRR TR000006

Maternal Exercise Improves Insulin Sensitivity in Mature Rat Offspring

Recent findings have shown that the intrauterine environment can negatively influence long-term insulin sensitivity in the offspring. Here we look at maternal voluntary exercise as an intervention to improve offspring insulin sensitivity and glucose homeostasis. Female Sprague-Dawley rats were split into sedentary and exercise groups with the exercise cohort having voluntary access to a running wheel in the cage before and during mating, pregnancy, and nursing. Female offspring were weaned into sedentary cages. Glucose tolerance tests and hyperinsulinemic-euglycemic clamp were performed in adult offspring to evaluate glucose regulation and insulin sensitivity. Adult female offspring born to exercised dams had enhanced glucose disposal during glucose tolerance testing (P < 0.05) as well as increased glucose infusion rates (P < 0.01) and whole body glucose turnover rates (P < 0.05) during hyperinsulinemic-euglycemic clamp testing compared with offspring from sedentary dams. Offspring from exercised dams also had decreased insulin levels (P < 0.01) and hepatic glucose production (P < 0.05) during the clamp procedure compared with offspring born to sedentary dams. Offspring from exercised dams had increased glucose uptake in skeletal muscle (P < 0.05) and decreased heart glucose uptake (P < 0.01) compared with offspring from sedentary dams in response to insulin infusion during the clamp procedure. Exercise during pregnancy enhances offspring insulin sensitivity and improves offspring glucose homeostasis. This can decrease offspring susceptibility to insulin-resistant related diseases such as type 2 diabetes mellitus. Maternal exercise could be an easy, short-term, nonpharmacological method of preventing disease in future generations.

Perinatal exercise improves glucose homeostasis in adult offspring

Emerging research has shown that subtle factors during pregnancy and gestation can influence long-term health in offspring. In an attempt to be proactive, we set out to explore whether a nonpharmacological intervention, perinatal exercise, might improve offspring health. Female mice were separated into sedentary or exercise cohorts, with the exercise cohort having voluntary access to a running wheel prior to mating and during pregnancy and nursing. Offspring were weaned, and analyses were performed on the mature offspring that did not have access to running wheels during any portion of their lives. Perinatal exercise caused improved glucose disposal following an oral glucose challenge in both female and male adult offspring (P < 0.05 for both). Blood glucose concentrations were reduced to lower values in response to an intraperitoneal insulin tolerance test for both female and male adult offspring of parents with access to running wheels (P < 0.05 and P < 0.01, respectively). Male offspring from exercised dams showed increased percent lean mass and decreased fat mass percent compared with male offspring from sedentary dams (P < 0.01 for both), but these parameters were unchanged in female offspring. These data suggest that short-term maternal voluntary exercise prior to and during healthy pregnancy and nursing can enhance long-term glucose homeostasis in offspring.

Influence of exercise-induced maternal stress on fetal outcome in Wistar rats: Inter-generational effects

The effects of physical activity during pregnancy and lactation on the fetal outcome and the growth of pups was studied in Wistar rats (n 144). Rats were trained to swim for 2 h every day, 6 d/week through pre-pregnancy, pregnancy and lactation. Maternal exercise during pregnancy, despite the dams having ad lib. access to food, resulted in low-birth-weight pups (5.6 (SD 0.7) g; n 178 in exercised dams v. 6.2 (SD 0.8) g; n 238 in sedentary dams). Maternal exercise continued through lactation exaggerated further the growth retardation of these pups (30.0 (SD 4.7) g; n 78 in exercised dams v. 36.0 (SD 6.9) g; n 126 in sedentary dams). The effects of maternal exercise during pregnancy and lactation studied over two successive generations revealed a reduction in the growth rates of the second generation progeny of both exercised (5.3 (SD 0.9) g; n 125 at birth and 25.1 (SD 6.8) g; n 54 at weaning) and sedentary rats (6.0 (SD 0.2) g; n 110 at birth and 31.3 (SD 4.3) g at weaning) born to first-generation exercised rats. While slower growth in the former indicates a cumulative effect of exercise stress over two generations, that of the latter indicates that the generational effects are manifest even though the dams of the F1 generation were not exposed to exercise stress during pregnancy and lactation. These findings suggest that the adverse effect of maternal exercise during pregnancy and lactation on fetal outcome in one generation is transferred to the subsequent generation.

Attenuation of ethanol toxicity in primary myocardial cell cultures from offspring of swim-trained pregnant rats

Primary myocardial cell cultures were obtained from 3–5-day-old offspring of Sprague-Dawley rats (dams) that were swim-trained during pregnancy. Lactate dehydrogenase (LDH) release, succinate dehydrogenase (SDH) activity, beating rates and morphology were examined after treatment of these cultures with ethanol concentrations of 600, 800 and 1000 mg/100 ml for 1, 4 or 24 hr. In these cultures, ethanol exposure had no effect on SDH activity, and LDH release was only observed after 24-hr exposure to the higher concentrations of ethanol. Vacuolization and granulation occurred only in cultures exposed to 1000 mg ethanol/100 ml for 4 or 24 hr and complete loss of beating was observed only after 24-hr exposure to 1000 mg/100 ml. In a previous study (Butler et al. Toxicology 1985, 36, 61–70), the same parameters of toxicity were examined in myocardial cell cultures derived from offspring of sedentary dams; the latter cultures exhibited extensive toxic effects on LDH release, SDH activity, morphology and beating activity within shorter times and with lower concentrations of ethanol. Thus, in this exercise study, patterns of ethanol toxicity were established and the data obtained suggest that maternal swim-training during pregnancy induces adaptations in the primary myocardial cells from the offspring, resulting in temporal protection from ethanol-induced damage.