摘要:

AbstractThe effect of dehydration on intrarenal blood flow was investigated in 11 dogs, using polarographic determination of H2‐gas desaturation for measuring local blood flow in inner cortex (ICF) and outer cortex (OCF). Dehydration was induced by 48 h water deprivation + 2–300 mg ethacrynic acid (EA) per os the day before the experiment. Compared to a control group (n = 9) ICF was markedly reduced to 2.40 ± 0.47 ml/min×g (control 3.23 ± 0.64) whereas OCF 3.29 ± 0.80 ml/min×g was nearly unchanged (control 3.59±0.85). The ratio OCF/ICF was increased to 1.37 (1.11). Further dehydration by hypertonic peritoneal dialysis for 3 h increased Hct to 60 ± 4 and further reduced OCF and ICF, without significant change of the OCF/ICF‐ratio. At Hct above 55 sudden and intermittent changes in local cortical blood flow were recorded randomly at individual electrode sites, showing ischemic periods lasting for 1 to 60 min. Such flow changes were observed in 13 of 14 expts. and were not accompanied by changes in RBF. It is concluded that moderate dehydration causes a greater reduction of ICF than of OCF. Severe dehydration gives in addition rise to patchy, intermittent ischemia in both cor

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb06006.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractCardiovascular and autonomic nervous responses to an injection ofE. coliendotoxin were followed for up to 15 min. in cats anesthetized with chloralose and given artificial respiration. Within 60 seconds, endotoxin induced a drop of aortic pressure, with simultaneous cardiac acceleration and slight central venous hypertension. There was an associated, almost complete cessation of the aortic arch baroreceptor afferentation. The cardiac sympathetic efferentation increased up to 1.4 times the control level at its maximum. The splenic sympathetic efferentation increased up to 10.6 times the control level at the end of the 15 min period, when the other parameters studied showed a trend to control level. The sympathetic autonomic system seems to be activated through cardiovascular receptors sensing hemodynamic changes touched off by endotoxin‐induced release of vasoactive substance

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb06007.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractForce‐velocity relations of K+‐contractures of longitudinal smooth muscle from rabbit urinary bladder were studied by isotonic quick release at 37°C. In order to minimize the influence of parallel elasticity the study was limited to the rising part of the length‐tension curve. The force‐velocity data fitted well with Hill's equation. The in situ length of the strip at a bladder volume of 10 ml is called L10. This length is 50% of that at which maximum active tension is developed. At L10Vmaxwas 0.29 muscle lengths per second and it was estimated to be 0.36 lengths/s at optimum length. Constant b in Hill's equation had a value of 0.052 L10/s and it was unaffected by length changes over the interval 0.69 L10‐ 1.44 L10. At L10a/Powas 0.17. In the interval given above, a/Podecreased with increasing length in proportion to the increase in Po, indicating that a was also length independent. According to Hill's equation [V = b(Po‐ P)/(P + a)], V should increase in proportion to (Po‐ P) when the muscle length is increased ifaandbare constants. Such a linear relation was found at shorter lengths but at lengths close to or at the length for maximum active tension, V increased more than (Po‐ P). Two possible explanations were considered; firstly that b/(P+a) increased, and secondly that the load on the contractile element could be less than P due to an influence of the considerable tension in the parallel elastic element at these lengths. The series elastic recoil of the active muscle amounted to 3–4% of the muscle length when releas

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb06008.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Abstract3 techniques for the measurement of testicular blood flow in anesthetized adult rats were compared. Direct measurement of testicular venous outflow yielded values more than 3 times lower than those obtained by Xe‐133 clearance and radioactive microsphere techniques due to the surgical procedures involved in spermatic venous cannulation. There was an agreement between flow values obtained with Xe‐133 clearance (17.8 ± 3.5 ml/100 g×min) and radioactive microspheres (19.9 ± 5.5 ml/100 g×min). A homogeneous distribution of microspheres to different segments of the testis indicates that Xe‐133 clearance is an adequate technique for testicular blood flow measurements. However, for some experimental purposes the radioactive microsphere technique is more versatile than Xe‐133 clearance because of its capacity of measuring several organ flows sim

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb06009.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe characteristics of 47 non‐medullated and 54 medullated fibres arising from the aortic arches of 6 hypertensive rabbits have been investigated. The threshold for activation of the aortic C‐fibres lay between 78 and 190 (mean 122) mmHg. The threshold for activation of 54 medullated aortic baroreceptors in the same animals was from 70 to 140 (mean 109) mmHg. At the awake mean arterial blood pressure (MABP) of these hypertensive rabbits (143 mmHg) all the medullated fibres were active as were 78% of the C‐fibres. In contrast in a group of normotensive animals 91% of the medullated and only 28% of the non‐medullated fibres were active. Pressure response curves were constructed for 19 C‐fibres and 12 medullated fibres from the hypertensive animals. At a MABP of 110 mmHg the firing in the non‐medullated fibres was 2.0 Hz as compared with 19.0 Hz in the medullated fibres and at the awake MABP mean firing was 9.0 Hz in the non‐medullated fibres and 48.0 Hz in the medullated fibres. The firing at awake MABP was considerably higher in the hypertensives (9.0 Hz) as compared with the normotensives (1.1 Hz). Thus these data indicate that although the aortic C‐fibres are reset in chronic hypertension, they are reset less than the medullated aortic baroreceptors from the same animal. It is suggested that arterial baroreceptor C‐fibres may have an important role in the tonic control of the circulatio

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb06010.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe possibility that acidosis inhibits lipolysis indirectly by causing ionic shifts or by favouring the accumulation of an inhibitor has been tested in isolated fat cells. Lipolysis induced by 3 μM noradrenaline (NA) was inhibited by 40–60% and that induced by 1 mM theophylline (THEO) by about 75% when the pH was reduced to 6.6. Lipolysis induced by NA+THEO was inhibited by 20–30%. Changing the concentration of Ca++or Mg++did not alter the degree of inhibition. Reducing the K+‐ion concentration enhanced the inhibitory effect of low pH on lipolysis induced by NA or NA + THEO, whereas cyclic AMP accumulation was uninfluenced. Omitting glucose from the incubation medium caused a slight enhancement of pH‐induced inhibition of lipolysis (from 60 to 70%, p<0.01). Reducing the concentration of albumin, which binds inhibitory substances such as FFA, reduced lipolysis more at normal than at reduced pH. At high FFA/albumin ratios (5 or above) lipolysis was similar at normal and reduced pH. The antilipolytic effect of decreased pH was equally pronounced in perifused fat cells, where inhibitory substances are not allowed to accumulate. Our results suggest that the antilipolytic effect of acidosis is mainly a direct effect of the increase in H+ion concentration. The inhibitory effect of acidosis on various responses to β‐adrenoceptor stimulation may be caused by a decreased formation of cyclic AMP in turn caused directly by the dec

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb06011.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractInnervated strips of longitudinal muscle of guinea pig ileum were incubated with3H‐choline in the presence of physostigmine, after which the efflux of tritiated metabolites was studied. Under resting conditions3H‐acetylcholine,3H‐choline and other tritiated metabolites were released into the incubation medium. Analysis of the kinetics of the release of the metabolites indicated that the release occurred from at least 2 different compartments. Under the unstimulated conditions used, between 72 and 78% of the radioactivity remained in a third, non‐releasable compartment. The release of3H‐acetylcholine showed spontaneous fluctuations which were positively correlated to spontaneous variations of the isometric tension of the preparation. Electrical field stimulation at low frequency (0.5 Hz) consistently increased the release of3H‐acetylcholine. The release of3H‐choline was increased only slightly or not at all by the electrical stimulation. For studying stimulation‐evoked release of3H‐acetylcholine, it is suggested that the measurement of the total quaternary amine release is of similar value to measurement of3H‐acetylcholine itself. This approach considerably simplified the method. During 5 consecutive stimulation periods of 150 pulses each, the increase in the release of total quaternary amines diminished with time. By taking into account the reduction of the stores of radioactivity in the tissue during the experiment, correction for the negative trend could be made. When the preparation was stimulated with between 30 and 3 000 pulses a close correlation was found between the increase in the release of total quaternary amines and the number of pulses delivered. The volley output of the quaternary amines was not constant, however, but diminished by increasing st

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb06012.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThree groups of mice were trained for 1, 4 and 5 months according to different running programs on a motor driven treadmill and the fatty acid oxidation capacity (FAO) and the activities of some enzymes of energy metabolism (cytochrome c oxidase, malate dehydrogenase, triosephosphate dehydrogenase, and lactate dehydrogenase) were determined fromm. quadriceps femoris(MQF). Endurance training increased the FAO [5‐month training, 4 days/week, 30 min/day 22% (p<0.05); 1‐month training, 7 days/week, 150 min/day 37% (p<0.001); 4‐month training, 5 days/week, 60 min/day 24% (p<0.05)]. The activities of cytochrome c oxidase and malate dehydrogenase increased approx. 30% (p<0.001) whereas triosephosphate dehydrogenase and lactate dehydrogenase activities were not prominently influenced by training. The predominantly red part of MQF of untrained animals oxidized palmitate four times faster than the predominantly white part. The activities of cytochrome c oxidase and malate dehydrogenase were two times higher showing pronounced FAO in the red part. Endurance training increased the FAO and activities of oxidative enzymes in the red and white parts and in the whole muscle relatively equally resulting in similar differences between the muscle types after training. The absolute increase in the FAO of the red muscle was, however, manyfold when compared in chemical units to the white m

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb06013.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe sensitivity to methacholine of the parotid glands in rats maintained on a liquid diet (aiming at sensitization) for a period of 2 weeks or 3–4 weeks was compared with that of the parotid glands in rats on a pelleted bulk diet (aiming at desensitization). In the rats on the liquid diet, it was found that the dose needed to evoke a just perceptible secretion of saliva was smaller, that the secretion started earlier and continued over a longer time period, and further that the amount of saliva secreted expressed per gland weight in response to submaximal doses of the sialogogue drug was bigger when compared with the rats on the pelleted bulk diet. These findings are interpreted as signs of a higher degree of sensitivity of the glands in the rats on the liquid diet than of those in the rats on the pelleted bulk die

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb06014.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractSerum zinc was measured in 154 male and 95 female blood donors. Men had higher serum zinc levels than women, the difference being statistically significant (p<0.001). The correlations between serum zinc and serum testosterone, serum zinc and serum FSH and serum zinc and serum LH were studied in 40 men aged 28–60 years and a statistically significant positive correlation was found only between serum zinc and serum testosterone in men of age 36–60 years (p<0.005). These results do not support the theory that slight zinc deficiency primarily effects pituitary gonadotropins but indicate that it would rather act on testicular le

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb06015.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY