摘要:

AbstractA fluorocarbon emulsion FC‐80 has been used as a substitute for erythrocytes in a synthetic nutrition medium inin vitroperfusions of isolated rat livers. The rate of albumin synthesis was estimated. After the first hour albumin was synthesised at a constant rate of 0.52 + 0.17 mg/h per 100 g of the body weight of the liver donor.14C‐lysine was incorporated into the circulating proteins linearly after the first hour. Other parameters tested were: levels of circulating proteins, urea nitrogen, glucose, glutamic‐pyruvic transaminase, excretion of bile, weight changes of the liver, and level of glycogen in liver tissue after perfusion. Histological examinations were also performed. The function of the liver was comparable with the findings of other investigators who used whole blood as the perfusate. As far as we are aware this is the first time that a rat liver has been maintained in good functional condition for over 6 hours duringin vitroperfusions with a synthetic medium that included an erythrocyte substitute. The method seems to offer great advantages for the study of metabolic proc

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05748.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractSingle unit activity in sympathetic nerve fibres was studied in microelectrode recordings from intact cutaneous nerves in alert man. 4 units exhibited a “spontaneous” discharge of very low frequency (not exceeding 15 imp/min) during resting conditions, whereas 4 other units were silent. Mental concentration and arousal stimuli of different types caused an increase in impulse frequency of spontaneously active units, and previously silent units started firing. In reflex responses to electrical shocks, deep breathing and loud noises, single units often fired repeatedly in bursts, the maximal instantaneous frequency observed being 35 imp/s. Intense reflex responses to electrical stimulation were sometimes followed by a suppression of spontaneous activity for 1–2 s. Some of the units probably had a sudomotor function, since the unit activity correlated well with changes in galvanic skin resistance recorded within the innervation zone of the explored nerve fascicle. The conduction velocity measured for 6 sympathetic units ranged 1.0–0

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05749.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractC unit responses to intradermal electrical stimulation were recorded with tungsten micro‐electrodes inserted percutaneously into intact human cutaneous nerves. An increase in discharge frequency was associated with a decrease in conduction velocity in unmyelinated fibres, and this phenomenon was used to identifyafferentC units which responded to both electrical and natural stimuli in the skin. Antidromic impulses inefferent,sympathetic fibres were also elicited by electrical stimulation in the skin as judged by latency changes or signs of collisions in the C responses associated with activity in sympathetic fibres. In this way, conduction velocities in distal segments of both afferent and sympathetic C fibres can be estimated. Furthermore, the possibility to differentiate afferent and sympathetic C units is of obvious importance for the study of their respective discharge characteristics and in psychophysiological studies in alert ma

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05750.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractOxygen binding curves were determined, at two plasma pH values in the range 7.0–7.5, each at twopCOavalues of 22 and 77 mm Hg, respectively, on human whole blood where the red cell 2,3‐diphosphoglycerate (DPG) concentration had been decreased to about 1 mmol/1 of packed cells and increased to about 9 mmol/1 of packed cells. Numerical values are given for the oxygen‐saturation‐dependant ligand interaction coefficientsAlogpOzl ApH, AiogpOzl/llog/>C02 and /llog/)02//llogDPG and their dependance on pH,PCO2and DPG, respe

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05751.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractBreath‐by‐breath analysis of tidal volume, VT, inspiratory duration, Tr, and expiratory duration, TE, was performed on cats under light pentobarbitone anesthesia or after decerebra‐tion before and after vagotomy. In response to step changes in inspired CO2VTchanges earlier and more rapidly than the corresponding changes in the timing. The VT–Tj points may thus form a ‘hysteresis loop’ embracing the volume threshold curve of Clark and Euler (1972). The transient responses were present also after peripheral chemodenervation and after bilateral vagotomy. In contrast to earlier papers vagotomized cats under pentobarbitone anesthesia often showed some decrease of T(with increased steady state CO2 levels. In decerebrate vagotomized cats T[was more independent of variations in steady state PCO2 levels, but after administration of pentobarbitone Ti showed some steady state shortening of Tj with increased CO2. It is concluded that the controller of depth and rate of breathing contains at least 2 functional components which depend on PCO2in such a way that they exert opposite effects on Ti which cancel out to a great extent and that this relative match can be disturbed by pentobarbitone. It is postulated that the transient increase in mismatch is due to the fact that the 2 (or more) CO2effects have slightly different dynam

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05752.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe time course of the volume threshold curve for the inspiratory off‐switch,i.e.the relationship between volume, (Vx) and inspiratory duration (Tj) with intact vagus nerves, was determined in steady conditions at different inspired CO2 concentrations and body temperatures in lightly anesthetized cats by means of ‘ramp’‐shaped inflations and deflations of different rise times. With intact vagal feedback the Vx–TT data points could be very well fitted to hyperbolas in all conditions studied. Changes in steady state FACO2 never caused any detectable influence on the volume threshold curves. Changes in body temperatures, in a range below the panting threshold, caused pronounced effects on the volume threshold curve which could best be characterized as a shift of the whole curve along the volume axis to lower values with increased temperature. Thus, at each rate of volume expansion the threshold for inspiratory off‐switch was reached earlier the higher the temperature. Also in the absence of vagal volume feed‐back Ti became correspondingly shorter with increased temperature which indicates that these temperature effects are mainly of central origin. The mechanisms for the CO2 and temperature effects on tidal volume and inspiratory duration

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05753.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractTo decide whether redistribution of filtrate between superficial (S) and deep (D) nephrons takes place when GFR is reduced by hemorrhagic hypotension (HH) the amount of filtered14C ferrocyanide precipitated as Prussian blue in single S and D nephrons was determined in rats during HH of 80, 65 and 50 mm Hg mean arterial pressure (AP). Marked filtration and urine flow persisted only in the AP 80 mm Hg group, whereas the major fraction of nephrons had ceased filtration in four out of live rats at AP 50 mm Hg. The distribution of radioactivity between S and D proximal tubules was not altered in any of the HH groups as compared to normotensive controls.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05754.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractC unit activity was recorded with microelectrodes from intact sensory fascicles in the human peroneal nerve. The analysis includes 46 afferent units with receptive fields predominantly on the dorsum of the foot and ankle. 16 units were tested quantitatively. Another 30 units were tested qualitatively by a combination of electrical and natural stimuli in the skin. This method was valuable for a reliable identification of activity in individual afferent C elements, when several C units with similar potential amplitudes responded to testing in the skin. The units were not spontaneously active at normal skin temperatures but one unit showed a low frequency discharge at a skin temperature of 22oC. Cooling by ether evaporation was an inefficient stimulus except for 2 units. Gentle mechanical stimuli did not activate any of the units, whereas afferent C unit impulses were induced by moderately intense mechanical stimuli, noxious heat and various chemical irritants. The sensations produced by stimuli inducing intense afferent C unit activity were reported as “burning or delayed pain”, whereas stimuli eliciting low frequency activity often were reported as “itch”. It is concluded that polymodal C receptors, similar with “polymodal nociceptors” in the cat and monkey, are numerous in skin areas sparsely covered with hairs on the dorsum of the foot and ankle in man, whereas no low threshold C mechanoreceptors were identified. The experiments do not exclude the possibility that both delayed pain and burning itch sensations may be mediated by different impulse patterns from polymodal

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05755.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractHypoglycemic release of gastrin has been supposed solely to be due to vagal release. In this report the atropine resistance of the gastrin response to insulin was examined. 9 normal subjects were studied twice. 0.2 IU of insulin/kg i.v. was injected in each study, but in one atropine (30 μg/kg i.m.) was injected prior to insulin. Serum gastrin concentrations were measured by radioimmunoassay. Blood glucose concentrations did not differ in the two studies. Atropine almost abolished gastric output of acid. Gastrin concentrations rose after insulin and slightly more after atropinization. In four of the subjects a second late gastrin increase was observed after atropine. It is concluded that in man a major part of the hypoglycemic release of gastrin is independent on a cholinergic mechanism

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05756.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe effect of sympathetic nerve stimulation on the microvascular red blood cell flow velocity was measured in cat omental adipose tissue. Electrical impulses of 10 V, 0.5–6 Hz were utilized to stimulate the appropriate branch of the splenic nerve. Microvascular velocities were measured in the transilluminated omental bursa in arterioles, capillaries and venules, on‐line, by means of a dual window television system. The responses noted were: 1) decrease in flow (75% of vessels); 2) no response (7%); and 3) increase (18%). The magnitude of the responses were in proportion to the stimulatory frequency. The disparity of responses may be related to previous morphologic observations on the non‐uniformity of innervation of canine subcutaneous adipose tissue. It is proposed that the various vascular reactions reflect the presence of compartments, in the same tissue, endowed with different sympathetic controls. Indexable words. Sympathetic activity, adipose tissue, capillary flow, lipolysis, television micro

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05757.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY