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H A Keizer

Publications and source records attributed to H A Keizer.

At least 37 records · Page 2Linked to original sources
PubMed1999

Three months use of third-generation oral contraceptives does not affect artery wall properties.

In several studies, artery wall properties have been shown to differ between men and women. It has been hypothesized that these differences may result from hormonal influences but, in a previous study, we were unable to detect any influence of the menstrual cycle on artery wall properties. Therefore, we investigated the differences in artery wall properties, if any, between the menstrual cycle and the use of a third-generation oral contraceptive for 3 months. We investigated the right common carotid (CCA) and femoral (CFA) arteries of normotensive young (18-25-y-old) women volunteers (n = 14). The arterial cross-sectional distensibility and compliance coefficients were determined by means of a specially designed ultrasonic wall-tracking device and automatic brachial artery cuff blood-pressure measurements. The menstrual cycles and the cycles during oral contraceptive use (30 microg ethinylestradiol and 75 microg gestodene) were monitored by ultrasonographic evaluation and the assessment of plasma levels of 17beta-oestradiol and progesterone. The distensibility and cross-sectional compliance coefficients of both the CCA and CFA did not differ significantly between the menstrual cycle and the use of oral contraceptives, despite different ovarian hormone levels. Brachial arterial blood pressure was also not affected. We conclude that 3 months use of a third-generation oral contraceptive does not influence the wall properties of peripheral arteries and cannot explain the observed difference between genders. The absence of a rise in blood pressure and the low androgenic profile of this specific oral contraceptive may have contributed to our findings.

Adolescent↗
PubMed1999

Pre-exercise ingestion of carbohydrate and transient hypoglycemia during exercise.

To study the occurrence and contributing factors of transient hypoglycemia after pre-exercise ingestion of glucose after a 4-hour fast, 19 well-trained cyclists ingested 50 grams of glucose dissolved in water around noon after having a normal breakfast. The ingestion of the glucose solution was followed by 30 minutes rest after which the subjects cycled for 40 minutes at 60% of the predetermined maximal power output. Every 10 minutes blood was sampled for determination of glucose, catecholamines, and insulin concentrations. In 6 subjects (hypo-group) plasma glucose levels dropped transiently below 3.0 mmol/l, while in the other 13 subjects (non-hypo group) plasma glucose level remained above this level. Although at the onset of exercise the plasma glucose levels were lower in the hypo-group, insulin levels were similar in both groups, suggesting a higher insulin sensitivity in the hypo-group. During exercise, norepinephrine was lower in the hypo-group, indicating a lower sympathetic activity in the hypo-group. The lowest plasma glucose levels in both groups were observed after 20 minutes of exercise, after which plasma glucose concentration returned to normal levels. It is concluded that pre-exercise carbohydrate ingestion after a 4-hour fast is sufficient to induce a transient hypoglycemia. The data suggest that the occurrence of hypoglycemia is determined by a combination of a high insulin sensitivity, a small amount of ingested glucose, and a low sympathetic activity.

Adult↗
PubMed1999

Influence of exercise and menstrual cycle phase on plasma homocyst(e)ine levels in young women--a prospective study.

Plasma total homocysteine (tHcy) has been identified as an independent risk factor for cardiovascular diseases (CVD). The difference in tHcy between the sexes has most often been related to the sex hormones, but also to a higher muscle mass in men. The purpose of this study was to assess the effects of acute exercise, brief exhaustive training, and menstrual cycle phase on circulating plasma tHcy concentrations. Fifteen untrained eumenorrheic women (mean age [+/-SD]: 18.7+/-0.4 yr, body fat: 25.8+/-3.4%, VO2max: 43.8+/-2.3 ml x kg(-1) x min(-1)) volunteered for the present study, which covered two menstrual cycles. During the second cycle the subjects participated in two exhaustive 5-day training programs on a cycle ergometer: one in the follicular (FPh) and one in the luteal phase (LPh). Pre- and posttraining plasma tHcy and total estrogen (E) responses were determined in blood samples obtained immediately before, during and immediately after incremental exercise to exhaustion. tHcy levels showed a large between-subject variation, but differences between FPh and LPh levels were consistent (P=0.063). Mean tHcy levels at rest were 9.44+/-1.65 micromol/L and 8.93+/-1.71 micromol/L during the FPh and LPh, respectively. Brief exhaustive training did not elicit any changes in plasma tHcy concentrations, although posttraining LPh E levels were lower (P<0.01). Overall, the differences between FPh and LPh values for tHcy and E were attenuated by training. Acute exercise increased plasma tHcy concentrations (P<0.001). At exhaustion, tHcy levels increased by 17% and 16% during the FPh and LPh, respectively. This was also significantly above tHcy levels at submaximal exercise (P=0.044). After a short period of training tHcy levels did not increase as much during acute exercise as they did before training; however, the increments were still significant (P=0.048). In conclusion, acute exercise in women produces significant increases in plasma tHcy concentrations, whereas brief exhaustive training does not significantly alter plasma tHcy levels. Our findings also suggest that plasma tHcy concentrations are menstrual cycle phase-dependent and that there is a close association between estrogen status and tHcy levels.

Adolescent↗
PubMed1998

Acute and sustained effects of isometric and lengthening muscle contractions on high-energy phosphates and glycogen metabolism in rat tibialis anterior muscle.

Previous studies have shown that lengthening contractions, in contrast to isometric contractions, readily result in sustained malfunctioning of the exercised muscles. The present study was performed to investigate whether an exercise period with many (240) lengthening contractions (LC) results in alterations in muscle high-energy phosphates and inosine monophosphate (IMP) content, different from muscles performing a few (60) lengthening or a few (60) or many (240) isometric contractions (IC). Moreover, we sought for a possible cause(s) of the inability to replenish muscle glycogen stores following LC. Rat tibialis anterior muscles were subjected in vivo to either 60 or 240 LC or IC. Structural muscle damage occurred only after 240 LC. The fact that tissue glycogen levels declined to a similar extent during LC and IC suggests that the energy demand was comparable during both types of exercise. Nevertheless, the observation that on the one hand tissue stores of adenine nucleotides showed a greater decline, and on the other hand the tissue content of IMP increased to a significantly higher level after LC than after IC, clearly indicates that muscle energy metabolism is more disturbed during LC than during IC. The high tissue levels of IMP may contribute to impaired mechanical function as previously observed in muscles subjected to LC. In contrast to 240 IC, 24 hours after 240 LC, tissue glycogen stores and high-energy phosphate levels were not restored to control values. The present findings indicate that depressed glycogen synthase activity and impaired activity of the mitochondrial marker enzyme cytochrome C oxidase probably contribute to a continuous disturbance of energy metabolism in the exercised muscles during the 24 hours following 240 LC.

Adenosine Diphosphate↗
PubMed1998

Responsiveness of plasma 2- and 4-hydroxycatecholestrogens to training and to graduate submaximal and maximal exercise in an untrained woman. Interuniversity Project on Reproductive Endocrinology in Women and Exercise.

A single-subject experimental design was used to obtain some preliminary findings on the plasma responses of catecholestrogens (CE) to acute exercise and brief, but exhaustive training on a cycle ergometer. One previously untrained eumenorrheic female (body fat: 26% VO2max: 43.3 ml x kg(-1) x min[-1]) participated in this study. Resting CE levels were for "total" (unconjugated + conjugated) 2-hydroxyestrogens (2-OHE) 162pg/ ml and 350 pg/ml in the follicular (FPh) and luteal phase (LPh), respectively. Plasma total 4-hydroxyestrogen (4-OHE) levels were 41 pg/ml in the FPh and 66 pg/ml in the LPh. For "total" 2-methoxyestrogens (2-MeOE), we found 257 pgl/ml in the FPh and 374 pg/ml in the LPh. Resting levels of 2-hydroxy CE following a period of brief, intensive training were decreased during the LPh (2-OHE: -38%; 2-MeOE: -19%), whereas 4-hydroxy CE were unaffected. After training, the formation of CE as expressed by the 2-OHE:E and 4-OHE:E ratios, was increased by 75% and 200% at rest, respectively. CE activity or O-methylation, as estimated from the 2-MeOE:2-OHE ratio, was higher following training (FPh: +22%; LPh: +30%). During acute exercise before training, we observed a small rise proportional to the exercise intensity in the plasma "total" primary estrogen concentrations (FPh: +28%; LPh: +16%), and no changes in either 2-OHE or 2 MeOE levels. Plasma concentrations of 4-OHE, however, doubled during maximal exercise intensity. The 2-OHE:E and 2-MeOE:2-OHE ratios did not alter during incremental exercise. Training effects on acute exercise responses were only noticed for 4-OHE, which contrary to pre-training conditions, now progressively decreased. The major findings of this study are that in response to training: a) during rest, a greater proportion of CE are formed from a lower amount of precursor hormone, b) the rate of O-methylation of CE increases.

Adult↗
PubMed1998

Lumbar bone mineral density in adolescent female runners.

BACKGROUND: The purpose of this study was to determine if there were significant differences in lumbar bone mineral density (L2-L4, g/cm2) or several hormones among 3 groups of adolescent females: 10 amenorrheic runners, 10 eumenorrheic runners, and 10 eumenorrheic controls. METHODS EXPERIMENTAL DESIGN: comparative. SETTING: Cooper Clinic, Aerobics Center, Dallas, Texas. PATIENTS OR PARTICIPANTS: The subjects were white, non-smokers, aged 15.1-18.8 years, who were not taking birth control pills. All amenorrheic runners had less than 5 menstrual period in the past year, averaging 2,4 periods. The runners averaged approximately 36 miles/week (58.1 km) during the last 9 months of their training season and had been running for 1-5 years. INTERVENTIONS: None. MEASURES: Lumbar bone mineral density (BMD), 10 hormones, percentage of body fat, and dietary intake were measured. RESULTS: Mean lumbar BMD (g/cm2) did not differ significantly among groups (amenorrheic runners = 1.134, eumenorrheic runners = 1.165, controls = 1.148). However, expected trends were observed. Compared to the controls, the amenorrheic runners tended to have lower lumbar BMD and the eumenorrheic runners, higher. Although there were significant differences in concentrations of five serum hormones measured, all mean hormonal values were within normal ranges. Calcium intakes were low for all groups. CONCLUSIONS: In this study, with its small number of subjects and great variability within each group, it was concluded that there is no significant difference among amenorrheic runners, eumenorrheic runners, and controls in lumbar BMD. However, a longer period of amenorrhea might result in significantly lower BMD for the amenorrheic runners.

Adipose Tissue↗
PubMed1997

4-Hydroxycatecholestrogen metabolism responses to exercise and training: possible implications for menstrual cycle irregularities and breast cancer.

OBJECTIVE: To investigate the behavior of C4-substituted estrogens, the so-called catecholestrogens, in response to acute exercise and training. The 4-hydroxyestrogens are known to have both a strong estrogenic potency and affinity for catechol-O-methyltransferase (COMT), the enzyme that deactivates catecholamines. DESIGN: A prospective trial covering three menstrual cycles: a control cycle, a moderate training cycle, and a heavy training cycle. PARTICIPANT(S): Six untrained, healthy, eumenorrheic women (mean pretraining maximum oxygen uptake: 40.9 +/- 4.9 mL/kg per minute, body fat: 27.9% +/- 3.6%) volunteered for this study. INTERVENTION(S): An incremental exercise test to exhaustion on a cycle ergometer, in the follicular and luteal phases, before and after a brief but exhaustive training program. MAIN OUTCOME MEASURE(S): Hormone measurements included follicular and luteal phase plasma E2, LH, catecholamines, PRL, total unconjugated and conjugated estrogens, total 4-hydroxyestrogens (4-OHE), and 4-hydroxyestrogen-monomethylethers (4-MeOE). RESULT(S): Pretraining baseline 4-OHE levels were significantly higher in the luteal phase (66 +/- 9 pg/mL; mean +/- SEM) than in the follicular phase (51 +/- 7 pg/mL). Pretraining and post-training baseline 4-MeOE values were below minimal detection limits (< 35 pg/mL). During incremental exercise, catecholamines, PRL, E2, unconjugated and conjugated estrogens, 4-OHE, and 4-MeOE always increased (the increases in 4-OHE during exercise were more pronounced before training, contrary to the 4-MeOE being most increased after training). The baseline 4-MeOE:4-OHE ratio (a measure of catecholestrogen activity) significantly increased with progressive training. CONCLUSION(S): Because 4-OHE have been shown to be able to control the hypothalamic gonadotropin oscillator and to stimulate the luteolytic prostaglandin PGF2 alpha, the acute exercise-induced increases of 4-OHE and their positive correlation with lactate levels may indicate a key process in the pathogenesis of exercise-associated menstrual irregularities. In addition, 4-OHE, when insufficiently O-methylated, are known to be capable of raising mutagenic superoxide free radicals and causing DNA damage that may lead to breast cancer. The results of the present study also may be of significance for the apparent protective effects of sports participation against cancer of the breast.

Adult↗
PubMed1997

Vascular and stimulation delays in dynamic musculoplasty.

BACKGROUND: Dynamic musculoplasty is increasingly being used to replace severely damaged muscle. Electrical stimulation induces a change in muscle composition from type II to type I muscle fibers. The aim of this study was to assess the optimal time to start stimulation and the beneficial effect of a vascular delay. METHODS: Both gracilis muscles in rabbits (n = 3 x 6) were wrapped around a double polyurethane tube, and leads were implanted together with a neurostimulator. Right muscles were electrically stimulated for 11 weeks, and left muscles served as controls. In group 1 the muscle was stimulated immediately after transposition, in group 2 it was stimulated after 6 weeks, and in group 3 a vascular delay was performed and stimulation was started immediately after transposition. RESULTS: During stimulation the percentage of type 1 muscle fibers increased from a mean of 4.6% to 41.9%. In group 1 there was significantly more change in muscle tissue. There were no significant differences in recorded pressures between groups. In group 1 the increase in amplitude during stimulation was significantly elevated (p < 0.05). The fatigue index in group 1, 259 (SE 130) seconds, was significantly lower than that of group 2, 515 (SE 102) seconds (p < 0.05). CONCLUSIONS: Compared with the methods used in groups 2 and 3, immediate stimulation (group 1) gives more change in muscle tissue, demanding a higher increase in amplitude to achieve sufficient contraction. The fatigue index is also impaired. Thus vascular delay, as presently applied, does not improve muscle function.

Animals↗
PubMed1997

Female sex hormones do not influence arterial wall properties during the normal menstrual cycle.

1. In previous studies, the elastic properties of the common carotid artery were found to differ between men and women. In these studies, however, the phase of the menstrual cycle was not taken into consideration. It was the aim of the present study to investigate the effect of changing ovarian hormone levels during the normal menstrual cycle on the arterial wall properties of female large arteries. 2. We investigated the elastic right common carotid artery and the muscular right common femoral artery of normotensive young (18-35 years) female subjects (n = 12). The arterial distensibility and cross-sectional compliance coefficients were determined by the use of a specially designed ultrasonic wall-tracking device and measurements of automatic brachial artery cuff blood pressure. The phase of the menstrual cycle was assessed by ultrasonographic evaluation and measurement of 17 beta-oestradiol and progesterone blood plasma levels. 3. The distensibility coefficient and the cross-sectional compliance coefficient of both the common carotid and the common femoral artery did not change significantly during the normal menstrual cycle despite evidently changing ovarian hormone levels. 4. We conclude that the menstrual cycle does not influence the arterial wall properties of either the elastic common carotid artery or the muscular common femoral artery.

Adolescent↗
PubMed1997

The Conconi test.

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Anaerobic Threshold↗
PubMed1997

Exercise-induced changes in enzymatic O-methylation of catecholestrogens by erythrocytes of eumenorrheic women.

The present study was designed to assess the effects of acute exercise and short-term intensive training on catechol-O-methyltransferase (COMT) activity. COMT inactivates catecholamines and converts primary catecholestrogens (CE) into their O-methylated form yielding the 2- (2-MeOE) and 4-methoxyestrogens (4-MeOE). Blood samples were obtained from 15 previously untrained eumenorrheic women (mean +/- SE, VO2max: 43.8 mL x kg-1 x min-1 +/- 0.6) before and after a 5-d intensive training period, at rest and during incremental exercise. COMT activity was determined in the erythrocytes (RBC-COMT) after incubation of blood lysate with primary CE. The formation of both 2- and 4-MeOE was significantly higher (P < 0.05) during the luteal (LPh) than during the follicular phase (FPh). The amount of 2-MeOE formed (FPh: 4.2 +/- 0.2%; LPh: 4.9 +/- 0.2%) was significantly greater than the produced amount of 4-MeOE (FPh: 1.4 +/- 0.1%; LPh: 1.5 +/- 0.1%) (P < 0.05). Both before and after training, incremental exercise did not significantly alter RBC-COMT activity although we observed a trend for RBC-COMT activity increasing proportionally with the exercise intensity. After a brief period of exhaustive training, during rest the formation of 2-MeOE (FPh: +16.7%, LPh: +15.7%) and 4-MeOE (FPh: +28.6%; LPh: +40%) was significantly (P < 0.05) increased. The results of the present study are consistent with earlier findings reporting increased plasma concentrations of O-methylated CE following training. It is concluded that RBC-COMT activity is increased by brief intensive training, but not by acute exercise. We speculate that an increase in COMT-catalyzed O-methylation of CE may indicate that less COMT is available to deactivate norepinephrine.

Adolescent↗
PubMed1997

Plasma 2-hydroxycatecholestrogen responses to acute submaximal and maximal exercise in untrained women.

Exercise-induced menstrual problems are accompanied by an increase in catecholestrogen (CE) formation. It has been hypothesized that hypoestrogenemia may be secondary to an increased turnover from estrogens to CE, which then may disrupt luteinizing hormone release. In addition, the strong affinity of CE for the catecholamine-deactivating enzyme catechol-O-methyltransferase (COMT) has led to speculations about their possible role in safeguarding norepinephrine from premature decomposition during exercise. We investigated whether acute exercise on a cycle ergometer produces any changes in CE homeostasis. Nine untrained eumenorrheic women (body fat, 24.8 +/- 3.1%) volunteered for this study. Baseline plasma CE averages for total 2-hydroxyestrogens (2-OHE) were 218 +/- 29 (SE) pg/ml during the follicular phase (FPh) and 420 +/- 58 pg/ml during the luteal phase (LPh). 2-Methoxyestrogens (2-MeOE) measured 257 +/- 17 pg/ml in the FPh and 339 +/- 39 pg/ml in the LPh. During incremental exercise, total estrogens (E) increased, but 2-OHE and 2-MeOE levels did not significantly change in either phase. The 2-OHE/E ratio (measure of CE turnover) decreased during exercise in both menstrual phases, whereas the 2-MeOE/2-OHE ratio (correlates with COMT activity) did not significantly change. These findings suggest that there is insufficient evidence to conclude that brief incremental exercise in untrained eumenorrheic females acutely produces increased CE formation.

Adult↗
PubMed1997

Effects of a training program on resting plasma 2-hydroxycatecholestrogen levels in eumenorrheic women.

Catecholestrogens (CE) represent a major metabolic pathway in estrogen metabolism. Previous information on CE and training is limited to two cross-sectional studies that did not involve standardized training. Our purpose, by means of a prospective design, was to evaluate the effects of a brief, exhaustive training program on resting plasma concentrations of 2-hydroxy CE. The experimental design spanned two menstrual cycles; a control cycle and a training cycle. The subjects were nine previously untrained, eumenorrheic women [body fat: 24.8 +/- 1.0 (SE) %]. Data were collected during the follicular (FPh) and the luteal phases (LPh). Posttraining FPh and LPh tests were held the day after the last day of a 5-day period of training on a cycle ergometer. Total 2-hydroxyestrogens (2-OHE) averaged 200 +/- 29 pg/ml during the FPh and 420 +/- 54 pg/ml during the LPh (P < 0.05). Levels of total 2-methoxyestrogens (2-MeOE) were 237 +/- 32 pg/ml during the FPh and 339 +/- 26 pg/ml during the LPh (P < 0.05). After training, although the plasma levels of 2-OHE significantly decreased (21%; P < 0.05) during the LPh, the actual CE formation (as estimated from the 2-OHE-to-total estrogens ratio) increased (+ 29%; P < 0.05). CE activity, as expressed by the 2-MeOE-to-2-OHE ratio, showed significantly higher values in both phases (FPh, + 14%; LPh, + 13%; P < 0.05). At the same time, resting levels of norepinephrine (NE) were increased by 42% (P < 0.05). CE strongly inhibit biological decomposition of NE by catechol-O-methyltransferase (COMT). Results of the present study suggest that, in response to training, CE are increasingly competing with the enzyme COMT, thus preventing premature NE deactivation.

Adult↗
PubMed1997

Responses of catecholestrogen metabolism to acute graded exercise in normal menstruating women before and after training.

It has been hypothesized that exercise-related hypo-estrogenemia occurs as a consequence of increased competition of catecholestrogens (CE) for catechol-O-methyltransferase (COMT). This may result in higher norepinephrine (NE) concentrations, which could interfere with normal gonadotropin pulsatility. The present study investigates the effects of training on CE responses to acute exercise stress. Nine untrained eumenorrheic women (mean percentage of body fat +/-SD: 24.8 +/- 3.1%) volunteered for an intensive 5-day training program. Resting, submaximal, and maximal (tmax) exercise plasma CE, estrogen, and catecholamine responses were determined pre- and post training in both the follicular (FPh) and luteal phase (LPh). Acute exercise stress increased total primary estrogens (E) but had little effect on total 2-hydroxyestrogens (2-OHE) and 2-hydroxyestrogen-monomethylethers (2-MeOE) (= O-methylated CE after competition for catechol-O-methyltransferase). This pattern was not significantly changed by training. However, posttraining LPh mean (+/-SE) plasma E, 2-OHE, and 2-MeOE concentrations were significantly lower (P < 0.05) at each exercise intensity (for 2-OHE: 332 +/- 47 vs. 422 +/- 57 pg/mL at tmax; for 2-MeOE: 317 +/- 26 vs. 354 +/- 34 pg/mL at tmax). Training produced opposite effects on 2-OHE:E ratios (an estimation of CE formation) during acute exercise in the FPh (reduction) and LPh (increase). The 2-MeOE:2-OHE ratio (an estimation of CE activity) showed significantly higher values at tmax in both menstrual phases after training (FPh: +11%; LPh: +23%; P < 0.05). After training, NE values were significantly higher (P < 0.05). The major findings of this study were that: training lowers absolute concentrations of plasma estrogens and CE; the acute exercise challenge altered plasma estrogens but had little effect on CE; estimation of the formation and activity of CE suggests that formation and O-methylation of CE proportionately increases. These findings may be of importance for NE-mediated effects on gonadotropin release.

Adolescent↗
PubMed1996

Body composition, cardiovascular risk factors and liver function in long-term androgenic-anabolic steroids using bodybuilders three months after drug withdrawal.

The purpose of this study was to investigate in a cross-sectional design body composition, muscle fiber characteristics, cardiovascular risk factors and liver enzymes in long-term androgenic-anabolic steroids (AAS) using bodybuilders three months after drug withdrawal (AAS group; n = 16) and in non-users (CO group; n = 12). Training and dietary data were collected in all subjects. Anthropometry included weight, height, 8 skinfolds and 11 circumferences. Percentage fat (%FAT), fat mass (FM) and lean body mass (LBM) were calculated. In a muscle biopsy from the vastus lateralis muscle water content, fiber type distribution and diameters of fiber type I and type II were determined. Age, height, training characteristics, nutrition, skinfolds, %FAT and FM did not differ between the groups. The AAS group had greater BW and LBM, and larger circumferences of thorax, waist, upper arm and thigh than the CO group. Muscle biopsy data were comparable, except for muscle fiber diameter of type I which was larger in the AAS group. No differences in serum values of total cholesterol, HDL-cholesterol and triglycerides, nor in systolic and diastolic blood pressure were observed. In both groups serum alkaline phosphatase and gamma GT were within the normal range. This study suggests that in long term AAS using body-builders, after a three months AAS free period, BW is greater than in non drug users. This is reflected in larger LBM, circumferences and diameter of muscle fiber type I. In addition, no differences in fat mass, blood pressure, lipoprotein profiles and liver enzymes exist between AAS users three months after interrupted drug use and their non drug using counterparts.

Adult↗
PubMed1995

Glucose and insulin responses after commonly used sport feedings before and after a 1-hr training session.

This investigation examined the plasma glucose and insulin response in 6 trained athletes after consumption of four commercially available sport feedings 2 hr before as well as immediately after 1 hr of running under common training conditions. Four feedings were compared: Feeding 1, 160 g CHO/400 ml; Feeding 2, 69 g CHO/400 ml; Feeding 3, 69 g CHO + 6 g protein/400 ml; and Feeding 4, solid 69 g CHO + 5 g protein + 4 g fat. Before the training session, there were no differences between the four sport feedings in the area under the glucose and insulin curves and the insulin/glucose ratio. However, after exercise, Feeding 2 resulted in a significantly greater area under the glucose curve compared with Feedings 1, 3, and 4 (respectively, 352 vs. 241, 251, and 182) and a significantly lower insulin/glucose ratio compared with Feeding 1 (respectively, 6.2 vs. 15.8). Therefore, it is concluded that the kind of sport feeding may influence postexercise glucose and insulin responses.

Adult↗
PubMed1994

Rat heart fatty acid-binding protein content is increased in experimental diabetes.

Cytoplasmic fatty acid-binding protein (FABP) was assayed immunochemically in hearts from rats with insulin-dependent (IDDM) or non-insulin-dependent diabetes mellitus (NIDDM). FABP contents were 34% higher in IDDM and 103% higher in NIDDM hearts than in respective age-matched controls. FABP levels returned to control values when islets of Langerhans were transplanted into diabetic IDDM animals. In the diabetic hearts the activity of fructose-6-phosphate kinase decreased (IDDM and NIDDM animals), while that of 3-hydroxyacyl-CoA dehydrogenase increased (NIDDM animals only). These data indicate that experimental diabetes induces a marked increase of the FABP content of rat heart and suggests that this protein is involved in the enhanced fatty acid utilization by the diabetic heart.

Animals↗