摘要:

AbstractMast cells from rat peritoneal and thoracic cavities were isolated and incubated with biogenic amines (dopamine [DA], noradrenaline [NAa]and 5‐hydroxytryptamine [5‐HT]) or their precursor amino acids. Competition for uptake, saturation of mast cell amine stores (for 5‐HT and DA), and blockade of uptake by metabolic inhibitors indicate that simple passive diffusion does not suffice to explain the uptake by mast cells of the amines studied. The uptake of 5‐HT and DA appears to primarily involve active transport, whereas the uptake of Hi and NA may preferentially operate by facilitated di

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1972.tb05321.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractThe cerebral effects of bilateral carotid artery ligation were studied in ligthly anesthetized rats, either alone or combined with moderate reductions in the mean arterial blood pressure. The relative decreases in cerebral blood flow were estimated from the a‐v differences for O2and CO2on the assumption of an unchanged cerebral metabolic rate. Ligation of the carotid arteries alone was found to decrease cerebral blood flow to about 50 % of normal, but to give no significant changes in the energy state of the tissue, as judged from the tissue contents of the ATP, ADP and AMP. When the cerebral blood flow was reduced further by means of an induced decrease in blood pressure, the energy state of the tissue was severely affected. At this point the cerebral venous Po2was reduced from about 50 to about 30 mm Hg. Since pure hypoxemia with a reduction of venous Po2to about 10 mm Hg can be tolerated without changes in the energy state of the tissue, it is concluded that ischemia may lead to a grossly inhomogenous reduction in the tissue perfusio

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1972.tb05322.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractThe concentration of triglycerides, phospholipids and carnitine was determined in red and white parts of the gastrocnemius muscle from rats with and without a period of training by running. Also the rate of lipolysis in adipose tissue was determined with and without stimulationin vitro. The concentration of triglycerides was reduced in the red and white muscle tissue but positively correlated to each other in white muscle tissue. This suggests that the white muscle tissue. Correlation analysis revealed no direct relationship between the spontaneous or stimulated rate of lipolysisin vitroand the triglyceride concentration in either type of muscle tissue. This suggests that the level of muscle triglycerides was influenced or deter‐mined by other factors than the rate of mobilization of fatty acids from the adipose tissue per se. The concentrations of carnitine and triglycerides were negatively correlated in red muscle tissue but positively correlated to each other in white muscle tissue. This suggests that the metabolic role of carnitine with regard to triglyceride metabolism differed between the two muscle types. The possibility was discussed that the capacity of the intracellular carnitine transport system for fatty acids into mitochondria of red muscle tissue increased in the course of physical training as part of an adaptation towards enhanced oxidative metabolis

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1972.tb05323.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractThe regulation of sound transmission through the middle ear of nonanesthetized rabbits was quantitatively investigated by comparing the excitation of the cochlea before and after surgical inactivation of m. stapedius and/or m. tensor tympani in the stimulated ear. The crossed middle ear reflex was used as a measure of the excitation of the cochlea to stimulation with pure tones in the range from 0.5 to 8.0 kHz at intensities up to 125 dB SPL. Sounds through this frequency range were attenuated above a level of 90 to 100 dB SPL. Low frequency tones (0.5 kHz) were attenuated by all levels of activity in the m. stapedius and m. tensor tympani. High frequencies were attenuated only by m. stapedius activity at high intensity levels above reflex threshold (20–30 dB). The m. tensor tympani had no influence on high frequencies, above 2.0 kHz. Improved sound transmission due to reflex activity was not regularly found. The efficiency of the regulation was regarded as high: a 1.0 dB increase in sound level in the ear canal gave only a 0.3 dB increase in the excitation of the cochlea (i.e. the regulating efficiency of the closed‐loop system was 0.7 dB attenuation per 1.0 dB increase in stimulus sound intensity). The regulating efficiency of the open‐loop system was about 2 dB/dB. The open‐loop gain was estimated to 4 during steady‐state. The oscillations in the middle ear reflex response were found to be generated in the m. stapedius feed‐back loop regulating the sound transmission through the middle ear. It was concluded that the function of the acoustic middle ear reflexes can be described as extending the dynamic range of the cochlea and adaptation and it may also be compared with the effect of lateral

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1972.tb05324.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractBlood lactate concentration (LA) was measured in 4 female and 3 male well‐trained subjects before and during 30 min of continuous treadmill running at 4 different speeds, demanding about 30, 60, 70 and 80% of the individuals' maximal oxygen uptake (Vo2max). The same subjects also performed in another series of experiments where maximal intermittent exercise preceded 30 min of running at the same 4 speeds, or resting in a chair. During continuous running, starting from resting conditions, the blood LA increased only slightly up to a critical Ievel (i.e. 60—80%) of Vo2‐max. From then on, a pronounced lactate production may occur. During the maximal intermittent exercise, blood LA increased to 130—220 mg/100 ml. In the recovery period,i.e. continuous running at the same 4 speeds, or resting in a chair, blood LA decreased towards resting values. The lactate removal rate was calculated from the rectilinear part of the curves describing the changes in LA with time, and expressed as mg/100 ml X min. The lactate removal rate was higher during exercise than during rest, and increased with increasing work load up to the same critical level (i.e. 60—80% of Vo2max), beyond which a reduction was observed. The highest removal rate was 8 mg lactate/100 ml x min at 63% of Vo2max (average values). These results indicate that human skeletal muscle possesses a pronounced capacity to oxidize lactate. Therefore, a production of lactate is possible even with no increase in the blood LA. These results also indicate that the skeletal muscle, rather than the liver, may be regarded as the main site for lactate removal during

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1972.tb05325.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractWith the tenuissimus muscle exposed for vital microscopy, the effects on macro‐ and micro‐circulation of aortic compression and of arterial bleeding were studied in cats anesthetized with chloralose. In the first case, arterial pressure in the hindlimbs was kept at 50 mm Hg for 2 ½ h and in the latter, the animal was rapidly bled with 40% of its total volume, and then observed for up to 4 h. — During aortic compression arterioles of 25 μm internal diameter increased their dimensions with about 40% and arteries of 70 μm with about 15%. The diameters of the venules showed a slight decrease. Linear flow rates in the capillaries decreased but there was an even distribution of the blood flow. No formation of thrombi was seen. — At arterial bleeding all the vessels first reduced their diameters during 10—20 min. Then arterioles of 25 μm diameter dilated, while the diameters of the other vessels remained reduced. In average the cats survived for 2 ½ h. Within a few minutes after the bleeding there was an adhesion of white cells to the venular walls and in later stages aggregates of red cells, platelets and white cells started to occlude most venules and capillaries leading to extensive “functional shunting” at t

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1972.tb05326.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractIn cats anesthetized with chloralose the lengths and diameters of the different vascular segments in the tenuissimus muscle were measured in the vital microscope. The flow characteristics, including red cell velocity, were registered. Fixed and stained muscle specimens were analyzed histologically as well as Indian ink‐perfused muscles treated according to the method of Spalteholz. The average muscle fibre diameter was 44 μm. 62% of the muscle fibres were red (48% B‐fibres, diameter 41 μm and 14% C‐fibres, diameter 26 μm) and the remaining 38% were white (A‐fibres, diameter 55 μm). The average muscle fibre was surrounded by 3.6 capillaries. The capillaries were 1015 ± 16.3 (S.E.) μm long and 5.3 ± 0.0(3) (S.E.) μm in internal diameter. The calculated capillary surface area was 0.9 m2/100 cm3of muscle tissue. Average red cell velocity in the capillaries was found to be 0.5 mm/s, but there was a wide variation with time and between different capillaries. Neither “spontaneous” changes in internal diameters of the microvessels nor a distinct precapillary sphincter activity could be observed. Arterio‐venous anastomoses within the muscle tissue

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1972.tb05327.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractThe responses of single units in the cochlear nucleus of the rat to sinusoidally amplitude‐ and frequency‐modulated tones and amplitude‐modulated broadband noise were studied. The distribution of discharges within a cycle of modulation was determined from cycle histograms locked to the modulation wave. In response to amplitude‐modulated tones and broadband noise, all units investigated showed a peak in the degree of modulation of the spike frequency within the modulation frequency range from 50 to 200 Hz. In many units the relationship between the degree of modulation of the stimulus sound and of the modulation of the resulting spike train was almost unchanged over a wide range of sound intensities. In other units, enhancement of modulation within a certain range of modulation frequency became more pronounced when the sound intensity was increased. This was mainly due to a suppression of modulation at lower modulation frequencies. The shape of the histograms was nearly sinusoidal even at modulation depths which resulted in nearly 100% modulation of the neural discharge frequency. The amount of modulation of the discharge frequency in response to frequency‐modulated tones was dependent on the frequency of the tone in relation to the CF of

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1972.tb05328.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractThe influence on the intraocular fluid dynamics (intraocular pressure, inflow and outflow) of one i.v. injection or a 3 day topical application of physostigmine, morphine, cyclopentolate or homatropine was investigated. Special attention was paid to the inflow of aqueous humour and ATPase activity in the ciliary body‐iris after administration of these drugs. Systemic injection of physostigmine caused a marked decrease in intraocular pressure, which seemed to be due to the decrease in inflow of aqueous humour. On the contrary, three day topical applications of this drug had no effect on the IOP or intraocular fluid dynamics. Intravenous injection of morphine increased both the inflow rate and the outflow facility of the eye. Cyclopentolate and homatropine did not decrease the outflow facility. However, cyclopentolate applied intravenously or topically increased both the inflow rate and the outflow facility slightly. Homatropine intravenously injected had no effect on the intraocular fluid dynamics but applied topically slightly increased the IOP, possibly due to the increased inflow of aqueous humour. None of these drugs caused any significant change in the NaK‐ATPase activity in the ciliary body‐iris. Physostigmine and morphine markedly reduced Mg‐ATPase activity. Physostigmine did not decrease Mg‐ATPase activity when the eye had been sympathectomized 7 days before administrations of the drug. It was concluded that the effect of physostigmine on Mg‐ATPase was possibly mediated by way of the sympathetic ner

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1972.tb05329.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractDL‐mevalonate‐2‐14C was administered parenterally to 2 rabbits and 5 groups of mice. In the rabbits the amount of labelled material recovered in the non‐saponifiable lipids of the kidneys exceeded that of the liver. Most of the renal radioactivity was found in the squalene, lanosterol and methostenol fractions whereas the major part of the labelled material in the liver was present as radioactive cholesterol. The distribution of radioactivity within the kidney and the liver in the mice varied with the size of the administered dose. The smaller the dose, the larger the proportion of label recovered in the kidneys. In all experiments most of the radioactivity of the liver was transformed to cholesterol. The conversion of squalene to cholesterol proceeded more slowly in the kidneys and 30 min after the administration of the mevalonate substantial amounts of radioactivity was recovered as labelled squalene and lanosterol. The importance of circulating mevalonate as substrate in the cholesterol synthesis of the kidney will be di

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1972.tb05330.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY