摘要:

The aim of the study was to determine the distribution, total number and size of different types of fibres in whole cross‐sections of female m tibialis anterior and to compare these data with previous results obtained from male skeletal muscles as well as with data on female muscles obtained by biopsy technique. The distribution of fibre types varied within the muscle cross‐sections, and the pattern was slightly different from that earlier described for male muscles (Henriksson‐Larsénet al.1983). No difference in mean fibre type occurrence was found between the left and right muscles of the females. The type 2 fibres varied in size in different muscle regions and were usually largest at the deep surface of the muscle. Both the total number and size of the muscle fibres were smaller in the female muscles than in the corresponding male muscles (Henriksson‐Larsénet al.1985a, b). This resulted in a 30–40% smaller value for the total muscle fibre area in the female muscles compared to the m

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07583.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Using a modification of the Sperber technique we studied cellular uptake of organic substances in the kidney. A test substance was mixed with an extracellular marker (ethylenediaminetetraacetate or inulin), both radiolabelled with an activity ratio close to 1, and injected into the renal portal system on one side via a leg vein. The animals were killed 1–10 min after injection and the radioactivity in different organs determined. Results showed significantly higher ipsilateral (injection) to contralateral (control) kidney ratios (substance to marker) at 1 min after injection for125I‐Na‐o‐iodohippurate (125I‐Hipp;P<0.001),14C‐tetraethylammonium bromide (14C‐TEA;P<0.001),3H‐dihydromorphine (3H‐DHM;P<0.01), and125I‐iothalamate (P<0.01), with a progressive decrease in injection kidney ratios for125I‐Hipp and14C‐TEA when death occurred after a longer period. Inhibition of renal tubular transport with novobiocin or mepiperphenidol markedly reduced 1‐ and 4‐min injection kidney ratios for125I‐Hipp and14C‐TEA, respectively. When death occurred after a longer period, ratios in both kidneys increased significantly for125I‐iothalamate. A good correlation was found between peak cellular accumulation in the kidney and excretion efficiency of test substances. Thus, the results indicate (1) that125I‐Hipp,125I‐iothalamate,14C‐TEA, and3H‐DHM were accumulated from the peritubular side of the nephron through the transport systems for organic acids and bases, respectively, and (2) that125I‐iothalamate also showed luminal uptake. In conclusion, this newin vivotechnique is simple and well suited for studying renal tubular accumulation of organic substances and offers the advantage of being able to

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07584.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

In eight anaesthetized cats, one dog and one pig the left adrenal was activated during a 5–15‐min period by splanchnic nerve stimulation (10–30 V, 0.2‐2 ms) at supramaximal frequencies (10–50 Hz) or by i.a. infusion of acetylcholine in high concentration (10‐4M). The catecholamine (CA) release, as recorded in the adrenal venous outflow, was characterized by a very steep rise to a peak (within<10 s), followed by a rapid decline which after 5–10 min continued as a ‘steady state’ secretion, still above prestimulatory level. The initial release curve satisfied the straight line equation logB=K√(σ ml) + logBmax, shown previously by us to be characteristic of the cation‐induced amine release from amine‐charged IRC 50 (a synthetic carboxyl cation exchanger resin) and from chromaffin granulesin vitrowhich occurred on superfusion of these materials with isotonic NaCl solution (Uvnäs&Åborg 1984a). The initial CA‐release, which depending on the intensity of the stimulus amounted to between 0.1 and ˜ 5% of the adrenal CA content is suggested to reflect the rapid depletion of a CA pool for immediate release composed of granules ‘lined up’ for secretion adjacent to the plasma cell membrane. On depolarization of this membrane the granules are assumed to become attached to it and CA release to occur as a cation exchange, between CA+in the granule matrix and Na+in the plasma or possibly K+in the cytoplasm. The transition from depletion to ‘steady state’ phase is assumed to reflect resynthesis or other compensatory refilling of the releasable depot evoked by its depletion. Cation exchange is suggested to be a general principle in the release of biogenic amines, including transmitter amines and other co‐store

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07585.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The effect of several crown ethers on the currents at the node of Ranvier was studied. At differing potencies they caused a time‐ and potential‐dependent inactivation of potassium permeability and a time‐ and potential‐independent decrease in sodium permeability. The relative effect on potassium and sodium systems varied and was not directly related to their ionophoric properties. A computer analysis indicated that the induced inactivation was dependent on the normal potassium activation me

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07586.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The effect of nephrectomy and ureter ligation on the concentration of endogenous plasma neurotensin‐like immunoreactivity (p‐NTLI) was studied in conscious rats by means of antiserum 17–8201 which detects NT(1–13) only, and antiserum 0–7709 which detects NT(1–13) and NT(1–8). The unstimulated p‐NTLI concentration did not change significantly during a 25‐h observation period following nephrectomy in comparison with sham operation. However, stimulation of the release of NTLI by intraduodenal administration of oleic acid (0.2 ml) resulted in significantly higher p‐NTLI levels in the nephrectomized rats than in the sham operated rats. Ureter ligation did not significantly affect basal or stimulated p‐NTLI. The data indicate that the kidneys play an important part in the elimination of p‐NTLI relea

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07587.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Experiments were performed on chloralosed cats with ligated adrenals. The peripheral ends of the preganglionic sympathetic nerves to the colon were stimulated and colonic motility was monitored by a volumetric method. Electric nerve stimulation with various intensities elicited inhibitory motor responses and occasionally contractions. Hexa‐methonium and/or guanethidine blocked all inhibitory actions and revealed pure excitatory responses at high stimulation intensities. These colonic contractions were inhibited by atropine. However, atropine‐resistant contractions were sometimes observed, predominantly in the colorectal region. Thoracic sympathetic nerves affected the motility in the proximal colon only, while lumbar sympathetic nerves acted on both proximal and distal parts. Strength‐duration relationships and sensitivity to local heating suggest that the excitatory responses are due to an antidromic activation of thin, possibly afferent nerve fibres. Small doses of substance P injected close i.a. induced colonic contractions unchanged by hexamethonium and/or guanethidine but sensitive to atropine. The neurally‐induced colonic contractions are suggested to be due to an antidromic activation of thin sensory neurons which in the periphery release substance P, in turn activating cholinergic motor neurons, thus constituting an axon reflex arrangement. The possibility of a similar axon reflex mechanism, associated to thin afferents, activating adrenergic inhibitory neurons at the prevertebral ganglionic level is di

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07588.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The present study describes the influence of β‐adrenergic blockade on glycogen utilization and lactate accumulation in skeletal muscle of exercising man. Twelve physically active men were examined during 25 min of continuous cycle exercise equivalent to 65% of their maximal oxygen uptake both with and without oral administration of 80 mg of propranolol (Inderal®). Heart rate, oxygen uptake, rate of perceived exertion (RPE) and blood lactate concentration were measured during exercise. Muscle biopsies were obtained from m. vastus lateralis after 5 and 25 min of exercise, β‐adrenergic blockade decreased steady state exercise heart rate by (mean + SD) 35 ± 10 beats min‐1(P<0.001) and oxygen uptake from 2.47 to 2.39 1‐min‐1(P<0.01). Muscle glycogen decreased from the 5th to the 25th min of exercise, and β‐blockade had no significant effect on this decrease. In contrast to without drug, β‐blockade resulted in a decrease (P<0.05) in muscle lactate concentration from the 5th (6.9 mmolkg‐1w./w.) to the 25th min (4.8 mmolkg‐1w./w.). Similarly blood lactate levels were lower (P<0.05) with than without β‐blockade in the last but not the first 10 min of exercise. The alteration in muscle lactate concentration pattern following β‐blockade, may imply that adrenergic effectsper secontribute to the stimulation of glycolysis during submaximal exercise, except in its earliest phase. Nevertheless, the effect is not great enough to produce substantial differ

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07589.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The applicability of radioactive microspheres in measuring cardiac output (CO) during haemorrhagic shock in the dog was studied. The COs thus determined were compared with CO values obtained simultaneously by the Fick method. In 13 animals simultaneous CO measurements by the two methods were performed prior to and after initial bleeding (down to a mean arterial pressure of 40 mmHg), at the termination of the hypotension period, and 5 and 60 min following blood reinfusion. An excellent correlation (r = 0.97) between the two methods was found for all determinations combined. Furthermore, during each of the five phases of the shock procedure no difference was observed between the two methods of measuring CO and the correlation varied from moderate to excellent (r= 0.61‐0.94). The results suggest that the microsphere method has a precision and validity comparable to those of conventional methods in measuring CO in situations when it is extremely low, as in haemorrhagic shock, in addition to having high accuracy in normal condition

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07590.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The cerebral blood flow is lower in spontaneously hypertensive rats than in normotensive anaesthetized and mechanically ventilated rats during bicuculline‐induced seizures, presumably due to the increase in vascular resistance in the hypertensive rats. This study investigates whether the hypertensive rats develop more severe derangement of the cerebral energy metabolites than normotensive rats because of the reduced cerebral blood flow. After 20 min of continuous seizure activity both normotensive and hypertensive rats had significantly decreased levels of phosphocreatine, ATP and glycogen as well as increased lactate and lactate/pyruvate ratio within the parietal cortex compared to controls. The metabolic disturbances were somewhat less pronounced in the hypertensive rats than in the normotensive rats. Thus, ADP was significantly increased in normotensive rats only and the lactate/pyruvate ratio was higher in the normotensive rats. We conclude that spontaneously hypertensive rats are not more prone than normotensive rats to derangement of cerebral energy metabolites during short term bicuculline‐induced seizures and that insufficient blood flow is not the primary cause of the metabolic alterati

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07591.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Contractile responses to electrical field stimulation of excised small mesenteric arteries and veins of the rat were compared when stimuli were delivered in irregular bursts or at regular intervals. Spontaneously occurring skin vasoconstrictor impulses in a few‐unit median nerve recording in man were stored on tape and used to trigger a stimulator. Two irregular stimulation sequences at average frequencies of 1.6 and 1.8 Hz, respectively, were used. In the arteries, average contractile responses were significantly greater at an irregular than at an even stimulation frequency, but in the veins, similar degrees of contraction were obtained with the two modes of stimulation. The frequency‐response relationships to continuous regular stimulation showed the artery to respond less than the vein at low frequencies. This apparently explains the difference in behaviour between the vessels to irregular stimulation. The results show that not only the number of impulses, but also their pattern of occurrence, may influence the degree of vasoconstriction. Thus, the normal irregular sympathetic discharge pattern in itself has a bearing on the physiology of neuro‐effector control mecha

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07592.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY