摘要:

AbstractRegional blood flow distribution in ducks was estimated from fractional distribution of Rb86CI. A comparison was made between normally breathing ducks and submerged ducks. The data document that conspicuous changes in regional blood flow take place upon submersion. The skin, skeletal muscle, and organs of the gastrointestinal system showed a marked decrease in activity in the submerged condition down to an average of 3.9 % for the gizzard, 29.4 % for skin excised from the thorax and 11.0 % for gastrocnemius muscle. Surprising exceptions to this were displayed by tissues in the cranial part of the animals. Thus both skin and muscle from the head region showed an increase in activity during submersion. The same was true for the excised eye. The esophagus similarly showed an increased activity in the submerged animals. The myocardium from both atria and ventricles showed a striking increase amounting to 4.1 times higher activity in the left ventricular myocardium in the submerged animals. The change in vasomotor constrictor tone taking place upon submersion is thus highly selective and possibly segmentally oriented giving an increase in peripheral resistance to most organs posterior to the heart while the most cranial tissues seem to be subjected to a general decrease in vasoconstrictor tone with an increased blood flow. Activity in the kidneys was markedly consistent and 9.1 % of the value found in normally breathing animals. The adrenals showed an interesting increase in activity on the average as high as 4.9 times the value in normally breathing animals.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1964.tb03945.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

AbstractAngiocardiography with simultaneous recording of arterial blood pressure has been done on unanesthetized ducks during submersion.The contrast density was increased in the inflow veins to the right atrium during submersion. Variable degrees of reflux and a delayed passage were commonly observed in the veins. The circulation time through the lungs was prolonged by a factor of 4–5 depending on the degree of bradycardia developed during submersion. The duration of the capillary phase was similarly 7 times longer during submersion. A smaller number of heart beats sufficed to propagate the contrast through the pulmonary circuit during submersion. The total size of the heart was always increased in corresponding phases of the cardiac cycle during submersion. The increase of the heart contour was most prominent on the right side of the heart. The changes in size of the left ventricle were more moderate, but disclosed a tendency towards an increased volume and a larger systolic residue during submersion. The pulmonary arteries showed far smaller vessel diameters in the submerged condition. The diameter reduction was most marked before the vessels entered the pulmonary parenchyma. The larger systemic arteries showed no apparent dimensional changes going from presubmerged to submerged condition.The results indicate an increased resistance to flow in the pulmonary vascular bed. The large increase in the size of the heart and an increased central venous pressure in the presence of an unaltered arterial pressure are strongly suggestive that neural and/or humoral factors are playing an important part in the instantaneous regulation of stroke volume during submersio

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1964.tb03946.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

AbstractA plethysmographic method is described which has been used for continuous recording of volumetric changes in the isolated calf muscles of cats. Venous outflow, arterial and venous pressures were measured simultaneously. Steady state exercise was mimicked by stimulation of the motor nerve. Changes occurring in the resistance vessels, in the capacitance vessels and in the capillary filtration coefficients were recorded. Exercise provoked a dilatation of the resistance vessels, an increase of the capillary filtration coefficient (dilatation of the precapillary sphincters) and a distension of the capacitance vessels. The degree of dilatation in all three vessel sections was related to the severity of exercise. It was shown that the increase in regional blood volume (dilatation of the capacitance vessels) is caused mainly by an increased pressure head reaching the capacitance vessels and not by an active venous dilatation. During exercise there was a net outward capillary filtration due to an elevated capillary hydrostatic pressure and augmented by an increased capillary surface area available to blood flow. The elevation of capillary pressure was caused by a dilatation, which affected the precapillary resistance vessels relatively more than the postcapillary.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1964.tb03947.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

AbstractTissue pressure is one of the determinants of capillary filtration and appears to be a major limiting factor of filtration exchange during muscular exercise. Since direct measurement of tissue pressure through a needle was considered impossible, an indirect method was developed to record tissue pressure in skeletal muscle during rest and exercise. This method is based on the fact that veins are normally collapsible and that the pressure inside patent veins can never be less than the extramural pressure i. e. tissue pressure. When the tissue pressure exceeds the central venous pressure, the pressure in the local veins is dictated by, and becomes a measure of the tissue pressure. Instead of measuring this pressure the changes in volume of the muscle were recorded plethysmographical‐ly and the pressure below which changes of central venous pressure did not influence volume was noted. This pressure was regarded as corresponding to the minimum tissue pressure. The maximum tissue pressure was obtained from distensibility curves for the veins. The accuracy of the method is about 2 cm H2O. During rest the tissue pressure was only little above zero and rose during exercise in relation to the amount of filtrate accumulated in the muscl

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1964.tb03948.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

AbstractIn exercising skeletal muscle fluid is filtered from the blood stream to the interstitial space. The filtration process is facilitated by an increase of the capillary filtration coefficient. This coefficient is dependent upon capillary surface area and capillary permeability. The present study was designed to ascertain whether the capillary permeability increases in exercising muscle. The permeability of the capillary membrane was studied in two dogs. Dextran of different molecular sizes was injected intravenously, after which the concentration of the dextran in pure muscle lymph was compared with that in arterial plasma. The ratio between these concentrations did not change significantly when exercise was simulated by repeated stimulation of the motor nerve. It is therefore concluded that capillary permeability does not change during muscular exercise.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1964.tb03949.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

AbstractDaily recordings of body temperature in male rabbits have been shown to vary cyclically. The mean length of these cycles is very close to that of the cyclic variations in the sexual functions of the male rabbit previously found. Further the coincidence in phase between the cycles of the body temperature and those of the seminal volumes is statistically significant.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1964.tb03950.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

AbstractThe concentration of triglycerides, cholesterol and phospholipids in plasma and in ultracentrifugally separated plasma lipoproteins was studied in normal persons during participation in 1962 and 1963 in a yearly skiracing. The skiing time was around 8–9 hours. In the group studied in 1962 as well as in the 1963 group there was a significant fall in the concentration of triglycerides and phospholipids in plasma. When the 1962 group was studied during ordinary activities with identical caloric intake and at identical times as during the skiing no significant changes were found in the plasma lipids. The most pronounced decreases of the plasma lipids was in the triglyceride fraction and this decrease was directly and highly significantly correlated to the fasting triglyceride concentration. About three quarters of the decrease in triglyceride concentration was due to a decrease in the amount of triglycerides in the very low density lipoproteins. The triglyceride concentration in the low and the high density lipoprotein classes also decreased. The decrease of triglycerides was directly correlated to the fasting level in each lipoprotein class. No significant changes were observed in the cholesterol content of any of the lipoproteins. The phospholipid concentration, however, decreased in all three lipoprotein classes. The most pronounced decrease of phospholipids was found in the high density lipoproteins. Mechanism(s) for these changes in the concentration of the plasma lipids and lipoproteins during prolonged, heavy exercise were discusse

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1964.tb03951.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

AbstractThe stimulating effects of DL‐isoprenaline and L‐adrenaline on oxygen consumption and lactic acid production were compared in experiments on rabbits. In doses which produced a submaximal response DL‐isoprenaline was, for both effects, 4–5 times as potent a stimulant as L‐adrenaline. Although the calorigenic action of isoprenaline was largely referable to increased lactic acid oxidation, the fact that isoprenaline, in the doses tested, markedly stimulated the heart rate suggests that an increased cardiac activity contributed to the calorigenic effect. Intra‐arterial infusion of isoprenaline into the brachial artery increased the elimination of lactic acid from skeletal muscle while commensurately augmenting the blood flow. It seems probable that the vasodilator effect of isoprenaline in the rabbit stemmed, at least in part, from increased lactic acid production in the skeletal muscle. — The relations for doses of L‐isoprenaline, L‐adrenaline and L‐noradrenaline which produced equal lactic acid producing and calorigenic effects in the ra

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1964.tb03952.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

AbstractA technique for isotonic and isometric recording of uterine contractionsin vivois described. No significant difference was found in the spontaneous contractions recorded simultaneously from the two horns by the two methods. On the other hand, differences were found in the responses to gradually increasing stimuli, such as increasing concentrations of noradrenaline or of increasing strength of stimulation of the hypogastric nerve. The isotonic response rapidly reached a maximum, whereas the isometric response increased more gradually. Since the isotonic response can be maximal in spite of submaximal activation, the isometric response is a more reliable quantitative measure, which is in agreement with previous findings within vitrorecording. However, for qualitative evaluation of responses near threshold stimulation, isotonic recording at low loads is preferable. Anesthetics administered i.v. in small doses to lightly anesthetized animals slightly enhanced uterine contractions, whereas deep anesthesia and local application of the anesthetics depressed the activity. Uterine motility is extremely sensitive to decrease in body temperature.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1964.tb03953.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

AbstractThe myometrial response to rapid distension consists of a quick contraction, the early stretch response, followed by an increase in the rhythmic activity. The latency and amplitude of the early contraction has been studied during increasing degrees of distension and during repetitive distensions. The frequency of the rhythmic contractions increases with increasing distension; the amplitude and the external work performed by each contraction at first increases and later decreases. Data obtained from isometric and isotonic recordings indicate that the pacemaker activity is not directly related either to the intra‐uterine volume or to the intra‐uterine pressure but rather to the tension in the myometrial cells. The independency with which the two horns respond to distension, the lack of effect of local and spinal anesthesia and of autonomic blocking agents indicates that the active response to distension is of myogenic origin. The intra‐uterine pressure is not maintained during constant distensicn but decreases at first rapidly, later more s

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1964.tb03954.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY