摘要:

AbstractA single i.v. injection of 8 mg/kg of Segontin caused a fall in the NA content of rabbit hearts to less than 10 per cent of their normal value in about 2 hrs. After 4 hrs the tissue content of NA started to rise again and after 24 hrs it had recovered to about one third of its normal value. An i.m. injection of 0.75 mg/kg NA 2 hrs after Segontin treatment, caused a temporary rise in the NA content of the heart to the normal value. NA was increased in the coarse particle fraction, the high speed sediment and in the particle free supernatant fraction of the heart after homogenization, indicating that the exogenous NA is temporarily filling the available storage sites. An i.v. infusion of NA (10 μg/kg/min for 20 min) caused an uptake of NA into the heart previously depleted by Segontin, followed by a rapid and then slower release of the NA. The uptake of 1‐NA and d‐NA and also of 1‐A and d‐A showed stereochemical specificity in favour of the 1‐isomers. Phenoxybenzamine blocked the uptake of NA into the heart of rabbits depleted by Segontin, whereas DCI had only a small blocking effect. Phenoxybenzamine by itself reduced the NA content of all fractions of

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1965.tb04083.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

Abstract1‐C14‐Stearic acid and H3‐palmitic acid in rat serum were injected i. v. into fasted and refed male rats and the disappearance of radioactivity from the blood, its tissue distribution and recirculation into the blood were studied. Stearic acid was taken up at a lower rate than palmitic acid. Five minutes after the injection about the same total amount of C14‐as of H3‐label was recovered from the fasted rats. At 320 min more C14‐label was left. This may be due to the less rapid turnover of the Stearic acid‐containing phospholipids compared to the glycerides. In the liver there was a marked preferential incorporation of stearic acid into the phospholipids, whereas the ratio of incorporated stearic acid to palmitic acid in the glycerides was low. This skewed distribution was also seen in the blood phospholipids and the blo

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1965.tb04084.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractH3‐palmitoleic and 1‐C14‐palmitic acid were simultaneously injected into fasted or refed male rats and the disappearance of label from the blood, the tissue distribution of label after 2 and 320 min as well as the recirculation of label into the blood were studied. It was found that the injected palmitoleic acid was taken up and oxidized at a higher rate by the cells than was the injected palmitic acid. At short times, more H3‐label than C14‐label was found in the neutral fat in most tissues, indicating that palmitoleic acid is preferentially incorporated into the glycerides. The total lipids of the heart contained more palmitoleic acid label than palmitic acid label in the refed rats. In all the mentioned respects palmitoleic acid was metabolized in the same way as oleic acid.A useful method for biosynthesis of labeled palmitoleic acid from labeled palmitic acid is

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1965.tb04085.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractThe concentration of FFA and glycerol in plasma and of glucose and lactate in blood was studied in 5 horses during exercise. The turnover of FFA was also determined. During exercise the efflux of FFA from plasma as well as the mobilization of FFA into plasma was increased. The glycerol concentration generally increased while the concentration of glucose fell. This decrease of glucose was very pronounced in 2 of the horses. The lactate concentration showed no consistent changes. When epinephrine was infused into 2 horses the concentration and the turnover of FFA as well as the concentration of glycerol increased. The concentration of glucose fell slightly while the lactate concentration increased significantly in response to adrenaline.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1965.tb04086.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractExperiments were performed on chloraloseurethane‐anesthetized, vagotomized cats. Changes in the level of adrenomedullary hormones were prevented. Distension of a segment of distal jejunum produced a prompt decrease in tone and rhythmicity in the proximal jejunum. This so called intestino‐intestinal inhibition is a propriospinal reflex response apparently mediated by sympathetic efferents. Electrical stimulation in the mediocaudal part of the rhomboid fossa was found to ‘block’ this spinal intestinoinhibitory reflex. The fact that bulbar stimulation alone sometimes produced an increase in gut motility seemed to be due to suppression of a prevailing activity in the propriospinal reflex. When there was a low level of such activity medullary stimulationper sehad little or no effect on intestinal motility. It is suggested that the supraspinal structures exert an inhibitory influence on impulse transmission in the propriospinal intestino‐inhibitory re

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1965.tb04087.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractUsing a plethysmographic method combined with recording of blood flow and, at times, recording of the volume of blood in the calf of the cat with an isotope technique, the responses of the resistance vessels, of the capillary filtration coefficient and of the capacitance vessels were studied when the vessels were subjected to the antagonistic influences of muscular exercise and vasoconstrictor fibre activity.At the higher frequencies of stimulation used sympathetic activation caused an equally marked reduction of blood flow during exercise as during rest, but during exercise the response of the resistance vessels subsided within a few minutes to become steady at a level only a little above starting level despite continued stimulation. The capillary filtration coefficient, already increased during exercise, was affected, and then increased still further only when the sympathetic were stimulated at such frequencies as impeded blood flow markedly. Sympathetic stimulation during exercise increased the tone of the capacitance vessels—a response that did not weaken at all so soon as that of the resistance vessels.It is concluded that the resistance vessels and particularly the precapillary sphincters are more sensitive to vasodilator metabolites locally released during exercise than to the vasoconstrictor fibre supply, while the reverse is true for the capacitance vessel

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1965.tb04088.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractCalf muscles of cats were perfused with blood at constant flow rates. Tissue volume, blood flow, arterial and venous pressures were measured. Exercise was imitated by intermittent contractions of the muscles. During contractions the potassium concentration of the venous plasma from the calf increased by up to 100 per cent. Potassium salts infused intra‐arterially at low rates dilated the vessels. It was calculated that the potassium released during exercise directly explains 25 to 65 per cent of the dilatation during exercise, the percentage being smallest when dilatation was slightest. There is presumably a diffusion gradient for potassium between tissue and blood with consequent underestimation of the role of the potassium ions, particularly when the dilatations are only weak. Therefore, 65 per cent probably comes closest to the true value of the proportion of the dilatation due to the potassium ions.Potassium infusions produced the same vascular response as exercise: a decrease of flow resistance was accompanied by a proportionate increase of the capillary filtration coefficient without signs of any increase in capillary permeability or dilatation of the capacitance vessels. Potassium is the only dilative substance hitherto found to produce exactly the same response as exercis

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1965.tb04089.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractIn cats anaesthetized with pentobarbitone lumbar motoneurones were impaled with potassium citrate microcapillaries. The inhibitory influence from muscle stretch receptors on the motoneurones was studied. Attention was paid to the following criteria: 1) mono‐synaptic excitability, 2) firing rate during stimulation by depolarizing transmembrane current, 3)“synaptic activation noise” and 4) shift of average membrane potential. A postsynaptic inhibition is described which is insensitive to convulsive doses of strychnine. This strychnineresistant postsynaptic inhibition was frequently found. So‐called presynaptic inhibition was never o

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1965.tb04090.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractThe effect of hypophysectomy on the fate of uniformly labelled14C glucose was studied in cerebral cortex, anterior and posterior hypothalamus, adrenal cortex and thyroid gland of rabbits. Determinations were also made of DNA content and oxygen consumption of the tissues. The findings after hypophysectomy were as follows: Oxygen uptake of all brain parts increased. The14COSproduction of the posterior hypothalamus was increased. Oxygen consumption and14CO2production decreased in adrenal cortex and thyroid gland. The formation of free14C alanine in the cerebral cortex decreased. The formation of14C aspartic acid in the posterior hypothalamus increased. In the adrenal cortex and thyroid gland a decreased conversion of14C glucose into all metabolites studied was found. The rate of formation of radioactive protein bound amino acids in the brain parts remained unchanged. In the proteins of adrenal cortex and thyroid gland hardly any radioactivity could be detected. The changes appeared to be closely correlated with the activities in various enzyme systems observed previously.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1965.tb04091.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractThe reactivity of the chick embryo erythron to varying ambient oxygen concentrations was investigated. The hemoglobin (Hb) concentration, the hematocrit and red cell count were determined in embryos incubated in 40 % O2, air and 15 % O2. The age of the embryos varied between 9 and 19 days. The results indicated that embryos weighing less than 7 g and approximately less than 14 days old do not increase their Hb, hematocrit or erythrocyte count when exposed to 15 % O2. In embryos aged 16 days or over the 15 % O2exerts a stimulatory effect: the Hb and hematocrit values exceed those found in the embryos incubated in 40 % O2. The mean corpuscular volume and the mean corpuscular Hb are not affected by differences in ambient oxygen concentrations.It is pointed out that the 15th day of incubation seems to represent a critical phase in chick embryo development—it is not only approximately the date when myeloid erythropoiesis begins to dominate, but also the date when, for instance, some polyamines begin to be synthetized and the hypophysis becomes functionally activ

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1965.tb04092.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY