摘要:

In the present study, we investigated the influence of estrogen on3H‐noradrenaline (3H‐NA) release induced in the oviductal isthmus by electrical stimulation, potassium and calcium. The fractional release of3H‐NA was measured in oviducts isolated from ovariectomized rabbits and from ovariectomized rabbits treated with estradiol cypionate, 70 μg/kg im 72 h before an experiment. Electrical field stimulation of the intramural nerves induced muscle contraction and augmented the release of labelled NA from the muscle. The3H‐NA release was reduced after estrogen treatment when reuptake of NA into the nerve terminals was blocked by desipramine, 10‐6M. Estrogen also reduced the3H‐NA release evoked by exposure of the oviducts to 121 mM KCI in the presence of calcium (2.5 mM) and in a high potassium, calcium‐free medium upon the addition of 2.5 mM calcium. In the presence of desipramine a small fraction of3H‐NA was released in high potassium, calcium‐free medium. This release was unaffected by estrogen. These results suggest that estrogen reduces the release of NA from the adrenergic nerves within the oviduct and that this action is exerted primarily on the calcium‐dependent release. It therefore might be due to a reduction in the entry of calcium int

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb00003.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The extensor digitorum longus (EDL) or soleus muscles of adult mice were cross‐innervated by the sural nerve (SN) and deprived of their original innervation. The number and sizes of motor units and the location of endplates in these muscles were studied 1.5 to 16 months later. In the EDL muscle, the SN cross‐innervated the original endplates. Very few ectopic endplates were seen, even when the nerve was implanted well outside of the original endplate area. Only 3% of the fibres were polyneuronally innervated. In the soleus muscle, however, the SN formed large numbers of ectopic endplates whether the nerve was implanted in the original endplate zone or outside of it. In addition, 20% of the muscle fibres were polyneuronally innervated. The SN cross‐innervated both EDL and soleus muscles completely. There was no preference for a particular group of the SN motoneurones since all the cross‐innervated muscles were innervated by all SN motor axons and the motor unit sizes of the SN were similar in the cross‐innervated EDL, and soleus muscles. It is concluded that intrinsic properties of a muscle determine the ability to form ectopic synapses. The distribution of the motor unit sizes is determined by the particular pool of motoneurones which innervates t

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb00004.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The acidification of the urine within the distal tubule ofAmphiuma meanswas studied with micropuncture techniques. Antimony microelectrodes calibrated in vivo were used for measuring the intratubular pH and samples were taken for the determination of Na+‐ and Cl‐‐concentrations and for determining buffer lines within the HCO‐3‐CO2buffer system. The TF/P Na+was used as a relative length determinator and a significant acidification along the length of the tubule was found. The pH in the tubule was more acid than samples equilibrated at blood Pco2. This disequilibrium can be described in terms of an imbalance within the Henderson‐Hasselbach formula or/and as a Pco2‐gradient across the tubular wall. The calculated Pco2‐gradient was found to be correlated to the arterial Pco2and the acidification to the arterial pH. The greatest pH‐gradient is generated in the collecting duct a

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb00005.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The effect of electrical vagal nerve stimulation on intestinal net fluid transport rate was studied in the small intestine of the cat. The splanchnic nerves were severed in all experiments. Absorption was quantified with a new gravimetric technique which made it possible to study fluid transport also during intestinal motility. The stimulation characteristics were varied to activate selectively low threshold fibres or low and high threshold fibres. The observations did not reveal any affects of low threshold stimulation on intestinal fluid transport whereas an inhibition was seen when also the high threshold fibres were stimulated. This inhibitory vagal mechanism could also be elicited after the administration of atropine. Atropine in itself increased “resting” net fluid absorption. The results speak against a role for vagal cholinergic mechanisms in the control of net fluid absorption. There seem, however, to be tonically active intramural cholinergic pathways and noncho‐linergic inhibitory vagal neurons of unknown physiological signifi

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb00006.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The effect of splanchnic nerve activation on intestinal fluid transport and intramural blood flow distribution was examined in the cat. Previous reports from our laboratory have demonstrated that splanchnic nerve activation increases fluid absorption. The present study was performed to elucidate the mechanisms behind this effect. The results showed an increase in net sodium and chloride transport on splanchnic nerve activation whether intestinal blood flow decreased or not. The effect on sodium transport was due to a decrease in lumen to tissue flux. The effect could not be explained by a decrease in local blood flow, as it was present despite constant blood flow in both the villous and crypt regions. No change was seen in the villous osmolality gradient on splanchnic nerve activation. On the basis of these findings, it is proposed that the in vivo effect of splanchnic nerve activation is due to a decrease in fluid and electrolyte secretion, probably occurring in the intestinal crypts.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb00007.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The effect of shortening during activity, previously characterized in vertebrate striated muscle, was investigated in the anterior byssus retractor muscle (ABRM) of the molluscMytilus edulis. This muscle is considered to have an essentially myosin‐linked Ca2+‐ regulatory system. Release steps of different amplitude were performed during isometric phasic contraction, and force redevelopment was recorded at a muscle length L1, defined as 90% of the muscle length at which a slight resting tension, approximately 1 mN, appeared in the presence of 2.5 × 10‐5M 5‐HT. Active shortening caused a graded depression of the contractile force without affecting the total duration of the mechanical response. Peak redeveloped force after muscle shortening of 0.06 L1and 0.18 L1was reduced by approximately 1.5% and 7.0%, respectively, of the isometric tension value at L1. The shortening effect was fully reversible, and had a lifetime of approximately 8 to 9 s. The depressant effect of active shortening was augmented at a reduced degree of activation of the muscle. The presence of caffeine and dantrolene and altered tonicity of the extracellular medium (0.9 T‐1.2 T) did not significantly affect the shortening induced depression obtained at maximum phasic activation of the preparation. The nature of the shortening effect is compared to that obtained in vertebrate striated muscle and is discussed on the basis of differences in Ca2+‐regulation of the contractile system in these

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb00008.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The concentration of prealbumin in plasma and the elimination from plasma and whole body of intravenously injected131I‐labelled rat prealbumin were followed in normal rats and rats subjected to fasting or acute inflammation. During fasting and inflammation the concentration of prealbumin decreased to about 50% of the initial value. It was concluded from the radioactive tracer experiments that decreased synthesis was responsible for the decreased intravascular prealbumin mass in the fasting rats. In these rats the plasma volume also decreased. In the rats subjected to inflammation, both a decreased intravascular fraction and a decreased synthetic rate of prealbumin seemed to contribute to the decreased intravascular mass of prealbumin. The total catabolic rate was decreased in these condition

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb00009.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Extracts of the proximal third of the duodenum from 8 antrectomized dogs with the gastrointestinal continuity restored by gastroduodenostomy (n=4) or gastrojejunostomy (n=4) as well as from 4 unoperated controls were subjected to gel chromatography. The eluates were all assayed using two different gastrin antisera, one directed against the COOH‐terminal end of gastrin and the other directed against the NH2‐terminal end of gastrin‐17. The gastrin component pattern was very similar in all antrectomized dogs regardless if they had a gastroduodenostomy or a gastrojejunostomy. Gastrin‐17 was found to dominate while the amount of gastrin‐34 was at most one tenth of that of gastrin‐17. Using the COOH‐terminal directed antiserum approximately 15% (mean value) of the total gastrin‐like immunoreactivity eluted in a peak appearing in the same region as the COOH‐terminal octapeptide of cholecystokinin. In unoperated control dogs the corresponding peak constituted approximately 70% (mean value) of the total gastrin‐like immunoreactivity. In two of the control dogs small amounts of gastrin‐like immunoreactivity appeared at the elution volumes of gastrin‐34 and gastrin‐17. In the duodenal extracts of all dogs gastrin‐like immunoreactivity was found between the elution sites of gastrin‐34 and gastrin‐17. This material probably represents cholecystokinin‐33. The present results show that the increase in duodenal gastrin found after antrectomy, which we have reported previously, is due ma

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb00010.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Starved rats sedated with a neurolept analgesic were subjected to hemorrhagic hypotension while receiving infusions of iso‐osmolar and hyperosmolar solutions. The hemorrhage model used resulted in similar residual blood volumes and hematocrits in all groups. The non‐metabolizable pentose, xylose, and glucose were used to induce a state of hyperosmolality, which was absent in those animals which received iso‐osmolar infusions (0.29 M xylose). After 45 mins hemorrhagic hypotension and a blood loss equal to 40% of the initial blood volume, the animals receiving the hyperosmolar infusions had a better cardiovascular status compared to those which received the iso‐osmolar infusions. The cardiac outputs and stroke volumes were higher and heart rate lower in the hyperosmolar groups. Evidence of better tissue perfusion was obtained in those animals with the induced state of hyperosm

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb00011.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Non‐starved (fed) and starved rats, sedated with a neurolept analgesic, were subjected to 45 min of hemorrhagic hypotension. The hemorrhage inflicted did not cause hypoxic changes, and left fed and starved animals with the same residual blood volume. Fed animals developed a state of hyperglycemic hyperosmolality and their free fatty acids tended to rise, while these observations were modified among starved animals. After 15 min of hemorrhage the cardiovascular parameters were the same in fed and starved animals, but at 45 min striking differences were observed. In fed animals, cardiac output, stroke volume, skin and muscle flows were substantially higher than starved animal values, while the latter animals had a higher heart rate and peripheral resistance. These effects are attributed to the state of hyperosmolality developed by the fed animals, and can explain the association between nutritional status and survival in hemorrhag

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1983.tb00012.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY