摘要:

Glycogen forms the smallest yet most labile energy substrate store. Therefore studying carbohydrate flux may be crucial to understanding the regulation of energy balance. Indirect calorimetry has been used to measure carbohydrate oxidation overnight and during exercise in nine fasted subjects. Overnight carbohydrate oxidation (averaging 2.85 ± 0.8 g h‐1) was assumed to be derived primarily from hepatic glycogen since subjects were inactive or asleep, and since glucose oxidized after gluconeogenesis from protein is measured as protein oxidation. Lower‐limb muscle glycogen stores were depleted by repeated 30‐min periods of cycle ergometry at 45%Vo2maxuntil exhaustion (8 ± 1 periods). The carbohydrate oxidation rate decreased as exercise progressed. Quadratic curves yielded a close fit to each individual's exercise carbohydrate depletion data (mean multiple correlationr= 0.9996) and provided excellent inter‐subject discrimination. Total (muscle plus liver) glycogen stores prior to exercise were estimated by extrapolation of the depletion curves to zero oxidation rate. This produced an estimate (174 ± 61 g) which compared well with predictions (208 ± 43 g) based on reference values for muscle mass and initial glycogen content. The results demonstrate that non‐invasive estimates of glycogen status can be obtained from accurate respiratory

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1993.tb09476.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

A non‐invasive method for studying the dynamics of post‐exercise carbohydrate storage by means of whole‐body calorimetry and13CO2breath tests is described. Seven untrained glycogen‐depleted subjects were offered naturally13C‐labelled high carbohydrate meals (97% by energy) at 30 min intervals for 5 h and asked to consume as much as possible. Mean intake averaged 757 ± 211 (SD) g. Exogenous carbohydrate oxidation over 16 h calculated from gas exchange and isotope ratio measurements averaged 161 ± 45 g, and endogenous carbohydrate oxidation averaged 31 ± 25 g. Net carbohydrate storage, calculated as the difference between amount ingested and oxidized, was 563 g which was more than twice the measured hepatic and muscle carbohydrate oxidized during the depletion phase. After correction for body size the major determinant of glycogen storage was the amount of carbohydrate consumed (r =0.97,P<0.001) which in turn was determined by each subject's dietary tolerance. Post‐repletion exercises (12 h after last meal) were used to remobilize freshly stored glycogen.13CO2enrichments indicated that a substantial part of the new glycogen was derived from the exogenous carbohydrate provided by the r

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1993.tb09477.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

The effects of exercise training on eicosanoid levels were studied in male Wistar rats. One‐month‐old rats were trained on a drum exerciser at an intensity of around 70% of maximal oxygen consumption for 10 weeks (60 min day‐1, 5 days week‐1) after familiarization. Some animals of the same age did not exercise and served as a control. Two days after training, several blood vessels, including thoracic aortae, inferior vena cavae, external iliac arteries, external iliac veins, common carotid arteries and jugular veins, were excised and incubated for 10 min. Basal release of prostacyclin from these vessels was determined using [125I]radio‐immunoassay (RIA) of 6‐keto‐PGF1α. The levels of plasma prostacyclin and urinary metabolites of prostacyclin and thromboxane were also determined by RIA. Our results showed that trained animals had lower body weight and urine II‐dehydro‐thromboxane B2levels than the controls (P<0.001 andP<0.05, respectively). In contrast, urinary 2,3‐dinor‐6‐keto‐PGF1αlevel was elevated after training (P<0.05). Nonetheless, prostacyclin levels in plasma and from various dissected vessel segments, except thoracic aorta, did not change significantly after training. These findings suggest that exercise training may affect endogenous eicosanoid levels by increasing the basal release of prostacyclin and reducing

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1993.tb09478.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Microsomes of bovine corneal epithelium metabolized [14C]arachidonic acid extensively to [14C]12‐hydroxyeicosatetraenoic acid. The biosynthesis was not stimulated by exogenous NADPH and it could be inhibited by over 90% with two lipoxygenase inhibitors, esculetin and eicosatetraynoic acid. Chiral phase high performance liquid chromatography showed that 12‐HETE consisted of the 125 enantiomer. The results indicate biosynthesis by 12S‐lipoxygenase of bovine corneal epithelium rather than by cytochrome

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1993.tb09479.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

The occurrence of the intermediate filament desmin in ovary and corpus luteum of pseudopregnant rats was studied using Western blot analysis and immunohisto‐chemistry. The luteal phase was induced by mating with vasectomized male rats and ovaries were studied after 6, 11 and 19 days. The findings from the Western blot analysis showed that desmin was present in the corpus luteum. Immunohistochemical localization of desmin showed two types of localization in the corpus luteum. The arteries around the corpus luteum, as well as arteries elsewhere in the ovary, had a high content of desmin in their muscle layer. Dispersed in the corpus luteum was an immunohistochemical staining of desmin that was localized mainly adjacent to the luteal cells. In the other part of the ovary a weak staining was registered in the theca layer, no staining in the granulosa layer and a streaky staining in the hilar region of the ovary.Desmin filaments are found in muscle cells of all types, including vascular smooth muscle cells. Probably, all desmin in the ovary is localized to smooth muscle cells with the possible exception of the corpus luteum where very few muscle cells have been identified. Localization to other vascular cells as endothelial is possible. In this study we found an increase in desmin content in the corpus luteum after day 6. If desmin is related to vascular resistance, our finding is consistent with the decrease in blood flow that occurs after day

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1993.tb09480.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

The effect of endothelin (ET), a recently discovered 21‐amino‐acid polypeptide with powerful vasoconstrictor properties, was examined on human uterine myometrial stripsin vitro. ET dose‐dependently (10‐‐11‐‐10‐‐7m) increased the contractile force (monitored as contraction amplitude) of the myometrium with significant effects at 10–8and 10‐‐7M. ET (10‐‐8m and up) also increased the basal tone of the myometrium.The calcium channel blocking agents nifedipine (10‐‐7m) and diltiazem (10‐‐6m) both inhibited the spontaneous tonic contractions of the myometrium. When ET was given in the presence of nifedipine, the tonic contractions were further inhibited, whereas the ET‐induced increase in basal tone remained. The same result was obtained with diltiazem (10‐‐6m). The results indicate that the contractility of human myometrium may be modulated by ET, and that the effects of ET on the human myometrium are only partly mediated by d

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1993.tb09481.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1993.tb09482.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY