摘要:

Electromechanical delays (EMD), the time from onset of EMG activity to change in acceleration or deceleration of the forearm, were studied in concentric and eccentric contractions of biceps and triceps brachii muscles. Horizontal flexion and extension movements were performed at varying speeds by 10 subjects. EMD time in concentric contractions for biceps was 41 ± 13 ms and for triceps was 26± 11 ms and was not influenced by the velocity of the movement. In eccentric contractions at the slower velocity the biceps EMD time was 38±13 ms and shortened to 28±10 ms at the faster velocity. The eccentric triceps EMD, however, was not significantly altered by movement velocity and averaged 30±7 ms. The data provided support for the hypothesis that stretching of the series elastic component, to a point where muscle force can be detected, is the primary determinant of the EMD phenomenon. However, there are complex interactions of the effects on EMD of muscle fiber type composition, whether the contraction is concentric or eccentric, and the velocity of the movement as well as possible gamma system influence. These complications require that consideration of electromechanical delay be made when phasic relationships between muscle force or joint torque generation from different muscles are inferred from

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06394.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Cerebral blood flow (CBF) and oxygen consumption (CMRO2) were measured during acute and long‐term ethanol intoxication in the rat. The purpose was to investigate whether the adaptive changes (development of tolerance) occurring in the CNS during ethanol intoxication were associated with changes in CBF and/or CMRO2. Consistent with other studies we found that acute severe ethanol intoxication (median blood alcohol concentration (BAC=5.4 mg/ml)) caused a significant decrease in CBF and CMRO2. After 3–4 days of severe intoxication (BAC of 6.6 mg/ml) these physiological variables were less affected indicating that functional tolerance had developed: CMRO2and CBF during acute ethanol intoxication were 9.3 ml/100 g/min and 60 ml/100 g/min respectively; after the long term intoxication period these variables reached 11.2 ml/100 g/min and 78 ml/100 g/min respectively, i.e. values not significantly lower than those of the control group. After induction of hypercapnia (PaCO2about 80 mmHg) CBF increased by 360% in the control group; in the acutely intoxicated group CBF increased by only 127% and in the long term intoxicated group by 203 % indicating that the cerebrovascular CO2‐reactivity had also adapted to the ethanol intoxication. It is concluded that adaptive changes of the CNS to chronic ethanol intoxication comprise alterations in CMRO2, CBF and cerebrovascular react

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06395.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Cods were equipped with cannulae for drainage of the stomach and for separate perfusion of the stomach and intestine. Acidity, volume, and osmolality of the gastric outflow were measured. During perfusion of the intestine with a near‐isosmotic saline (1 part sea‐water, 2 parts distilled water, '33% SW) and the stomach with pure (‘100%’) SW, gastric acid output was high and volume output slightly above the infused volume. The osmolality of the gastric perfusate decreased during passage of the stomach. It was concluded that no drinking occurred, and that the decreased osmolality was due to dilution by gastric secretions and osmotically lost water. When substituting the isosmotic intestinal perfusion to a dehydrating perfusion (100% SW), gastric acid secretion was depressed but volume output was unaffected. Also perfusion of the intestine with acidified 33% SW depressed gastric acid secretion and in addition increased volume and osmolality of the gastric outflow. The results suggest that perfusion of the intestine depresses the drinking reflex and that this depression is surmounted by intestinal acidification. Possible mediators of the intestinal feed‐back mechanism for the inhibition of gastric acid secretion are

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06396.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The present observations indicate that sulfonuric drugs release gastrin both from peripheral nerves in striated muscles and from endocrine‐like cells in the gastrointestinal tract. Gastrin appears in perfusates of extirpated cat legs after administration of tolbutamide or glibenclamide (5–50 μg/kg or 5–500 μg/kg perfused tissue respectively) to the perfusion medium. Furthermore gastrin is released into the portal vein of cats after i.v. administration of glibenclamide (5–50 μg/kg). The finding that sulfonuric drugs not only release insulin from β‐cells in the pancreas, but also gastrin from gastrin producing cells in the stomach as well as from nerve fibers in the skeletal muscles, indicate that sulfonuric drugs have more wide spread effects than previously assumed. Possible consequences of the drug induced release of peptides from peripheral nerves as well as of the release of gastrin from the gastrointestinal tract

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06397.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The importance of the adrenergic vasomotor nerve supply for the vascular ontogenetic development has been studied in the isolated portal vein preparation from rats, at 5–6 weeks of age, who had either been chemically sympathectomized by a series of postnatal 6‐hydroxydopamine (6‐OHDA) injections or been receiving the solvent alone. It was found that 6‐OHDA treatment largely, but not completely, prevented the outgrowth of the terminal NA fluorescent ground plexus. Nevertheless, the media underwent a seemingly normal differentiation into two layers. Functionally, the portal vein from the 6‐OHDA treated animals displayed weak and non‐persistent myogenic spontaneous activity; sensitivity to exogenous noradrenaline (NA) was increased 3‐fold and maximum stress was increased by 25 % as compared to control. Responses to transmural field stimulation were only obtained at high impulse rates and the maximum response was attenuated. Considering the very sparse adrenergic innervation following 6‐OHDA they seemed surprisingly large, however, but since they were abolished by tetrodotoxin and by phenoxybenzamine responses are concluded to be neurogenic and adrenergic in origin. A singular attenuation of neurogenic responses by atropine was found in 6‐OHDA treated vessels but not in controls. It is concluded that the adrenergic vasomotor nerve supply seems to exert some trophic influence during ontogenetic development but that the morphologic vascular development is largely governed by other, non‐neurogenic mechanisms. As to functional development, 6‐OHDA induced sympathectomy causes impaired development of phasic myogenic activity whereas maximum stress is augmented as is the tissue sensit

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06398.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The dynamics of amylase release from the guinea pig submandibular gland were studied in vitro by applying a multi‐channel microperifusion set. This technique makes it possible to measure time related enzyme release more accurately and to take samples of perifused tissue at short intervals. Stimulation of the ^‐adrenoceptor with norepinephrine gives rise to a rapid initial enzyme discharge, detectable within 15 s. Administration of propranolol inhibits enzyme release, which is not restored after removal of the agent. Simultaneous measurements of tissue cyclic AMP during norepinephrine stimulation at various time intervals display a significant increase of cAMP as early as 15 s after stimulation of secretion. This increase of cAMP thus coincides with the discharge of amylase. In addition, cAMP continuously accumulates during 30 min of norepinephrine perifusion of the slices. The present study describes a valuable tool with high sensitivity for visualizing the relations between enzyme secretion from the salivary gland and the intracellular biochemical processes. The data obtained further indicate a close correlation between amylase and cAMP during the initial phase of enzyme discha

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06399.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The transformation of [l‐14C]arachidonic acid by homogenates of human umbilical arteries was studied. The major compund formed was the stable end product of PGI2, i.e. 6‐keto‐PGF1α(lactol form) as analyzed by gas‐liquid chromatography‐mass spectrometry. PGI2was generated by incubating PGH2with a lyophilized pig aorta microsome preparation. PGI2concentrations around 10 ng/ml relaxed the human umbilical artery preparation significantly. Formation of PGI2by umbilical arteries during pregnancy might be a mechanism for regulation of blood flow to

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06400.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

10 anesthetized dogs were provided with acute common bile duct fistulas and the gallbladder was excluded. Hepatic bile output and biliary content of sodium, potassium and amylase were studied. 6 caval infusions were administered of CCK, 0.3 Ivy U‐kg‐1min‐1, with a superimposed infusion of SP, 20 ng kg‐1min‐1. 7 caval infusions were given of VIP, 50 ng‐kg‐1min‐1, with a superimposed infusion of SP, 20 ng·kg‐1min‐1. CCK increased bile output and biliary content of sodium, potassium and amylase by 78–110%. The corresponding increase induced by VIP was 55–85%. Biliary pH was not influenced. SP abolished the effects of both CCK and VIP. It is suggested that all peptides studied influenced canalicular bile secretion by changing t

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06401.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The effects of prolonged treatment with 1,3‐diaminopropane, a structural analogue of putrescine, on polyamine metabolism and growth in kidney tissue, were studied in mice in which renal hypertrophy was induced by testosterone treatment. Injections of 1,3‐diaminopropane resulted in an almost total suppression of the testosterone induced stimulation of ornithine decarboxylase activity and prevented the accumulation of putrescine and spermidine in the kidneys. Renal spermine concentration was even lowered. Administration of 1,3‐diaminopropane effectively prevented the testosterone induced increase in renal weight and RNA. In mice receiving 1,3‐diaminopropane proteinuria was observed and histological examination revealed renal damage. Due to the nephrotoxic action of 1,3‐diaminopropane caution is essential in relating the prevention of renal hypertrophy and the inhibition of polyamine

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06402.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The capacity of the human forearm and kidney to synthetize different prostaglandins (PGs) was studied, together with the quantitative relationship between the various PGs formed in these organs.14C‐labelled arachidonic acid (14C‐AA) was infused in healthy male volunteers at a constant rate into the brachial or the renal artery, with simultaneous sampling of regional venous blood. The venous plasma content of14C‐PGs was extracted, separated with thin‐layer chromatography (TLC) and quantified using fractionated liquid scintillation spectrometry. Most of the14C‐AA infused was metabolized and radiopeaks parallel to unlabelled standards of PGD2, PGE2, PGFja, 6‐keto‐PGF, and 13,14‐dihydro‐15‐keto‐PGEj (Me) were obtained. The chromatograms of both the forearm and the kidney plasma contained all the peaks described, but the relative distribution of theI4C‐PGs differed between the two tissues. In the cubital venous plasma, the main PG (apart from Me) was 6‐keto‐PGFla, indicating a considerable synthesis of PGI2in the forearm. In the renal venous plasma, on the other hand, PGD2accounted for the largest part of the authentic14C‐PGs found. Besides the tissue differences, large inter‐individual variations were observed. The results demonstrate the existence of both a considerable tissue specificity and an appreciable inter‐individual variation in the loc

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06403.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY