摘要:

AbstractThe adrenergic neuronal selectivity of3H‐outflow elicited by electrical‐field stimulation of rabbit isolated pulmonary artery preloaded with3H‐(‐)‐noradrenaline (3H‐NA) was examined. Following incubation (45 min) of arterial rings at 37°C with3H‐NA (10‐6M) and a 100 min wash‐out period, the sympathetic neurones were stimulated selectively and supramaximally, as regards tension development, with a constant current (250 mA; 300 monophasic pulses; 10 Hz; 0.3 ms). The initial stimulation‐induced3H‐outflow was higher than the subsequent 5 outflows, which remained almost constant (39, 20, 19, 17, 16 and 16 pmol g‐1, respectively).3H‐NA and3H‐O‐methylated plus deaminated metabolites constituted 11% and 74%, respectively, of the total3H‐outflow induced during the initial stimulation period, but 38% and 38%, respectively, during the second stimulation period. Omission of Ca2+in the physiological salt solution reduced the 6 stimulation‐induced outflows to 67, 40, 35, 24, 21 and 21%, respectively, of the untreated preparations. Bretylium (3 × 10‐5M) or tetrodotoxin (10‐6M) reduced the3H‐outflow to approximately the same extent. Stimulation‐induced outflows from artery rings preloaded with3H‐NA in the presence of cocaine (10‐3M) or in the cold (3°C) approximated the Ca2+, bretylium and tetrodotoxin‐insensitive release. These treatments all completely blocked the neurogenic contractile response. When artery rings were preloaded with3H‐NA in the presence of normetanephrine (10‐4M), the stimulation‐induced Ca2+‐insensitive outflows were markedly reduced. The results suggest that the field stimulation

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05992.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe synthesis of poly(A) containing RNA was increased in heart of non‐digitalized and digitalized rats after aortic constriction, the increase being of the same degree as that of the RNA lacking this sequence. No differences were found, either in the absence or presence of polyuridylic acid, in the incorporation of radioactivity into protein by cardiac ribosomes isolated from animals treated differently. It may be concluded, that after the constriction of the aorta the synthesis of mRNA proceeds at a similar rate as that of the bulk RNA, and that the treatment of the animals with digitoxin does not abolish the stimulus for hypertroph

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05993.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractIsometric peak twitch force (stimulation frequency 0.5/s; 29.5–30.5°C) was correlated with sarcomere length in isolated papillary muscles of the rabbit. Sarcomere length was measured from photographic recordings (1.5 ms exposure time) performed at rest between contractions and at the time of isometric peak twitch force. The sarcomere length at rest was found to be relatively uniform throughout the preparation and to be linearly related to the overall muscle length within the range Lmax‐ 0.85 Lmax. The distribution of sarcomere lengths increased considerably as the muscle went from rest to activity. Studies of surface markers showed different degrees of shortening (or elongation) of individual segments along the length of the preparation. The meanrestingsarcomere length at Lmax(the optimum muscle length for force production) was 2.44±0.01 μm (grand mean ± S.E., 7 muscles). The meanactivesarcomere length at Lmaxwas 2.29 ± 0.04 /μm. Active force declined steeply as the muscle length was reduced below Lmax. At a resting sarcomere length of 2.0 μm, active force was approximately 1/3 of the maximum. The observed differences between the length‐tension relationships in myocardium (twitch responses) and skeletal muscle (tetanic contractions) are discussed on the basis of a length dependency of the activation process in ca

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05994.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractIn chloralose‐anesthetized, adrenalectomized cats, the sympathetically conveyed effects of topical hypothalamic stimulations on gastric volume, blood pressure and heart rate were systematically explored. The vagal nerves were cut but could be kept active by graded efferent stimulation. In the absence of such vagal activity, hypothalamic stimulation had no appreciable influence on gastric volume, even though the stomach maintained considerable myogenic tone. When, however, a vagal excitatory activity was present, hypothalamic stimulation could markedly affect gastric tone, indicating that the sympathetic fibres exert their inhibitory influence on the stomachviaits cholinergic intramural neurons. Hypothalamic stimulations that induced reductions in pressure or heart rate also usually caused an enhancement of gastric tone. Similarly, pressor responses were associated with decreases in gastric volume whereas stimulation‐induced tachycardia was not linked to any particular type of gastric response. Thus, the hypothalamic sympathoinhibitory influences on the cardiovascular system seem closely connected to a suppression of the sympathetic outflow to the stomach. There is, on the other hand, no regular association between hypothalamic sympatho‐excitatory influences on the cardiovascular and gastrointestinal systems; in fact, there is in many areas even a suppression of sympathetic discharge to the stomach in association with cardiovascular stimul

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05995.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe influence of extrinsic innervation on bladder wall tension (tonus) and on intravesical pressure patterns was studied with a new cystometric procedure (Controlled Slow Cystometry, CSC) and during natural filling. After parasympathectomy, but not after sympathectomy, the basal intravesical pressure was markedly increased. At low filling rate the partial or completely denervated bladder was filled from small initial volumes without any increase in intravesical pressure. At higher rates of filling a pressure rise occcurred, and this reaction was not affected by either parasympathectomy or sympathectomy. As in the intact cat, the new pressure level was retained when the filling rate was gradually reduced. The various intravesical pressure patterns observed during filling were preserved in the partial or completely denervated organ. Thus, bladder adaptation during natural filling occurs independently of extrinsic innervation.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05996.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractGastric acid secretion was measured in swimming codfish surgically equipped with a catheter draining the stomach. Gastric acid secretion was stimulated by histamine (5 or 15μg/kg‐h) or by carbachol (5μg/kg‐h). Pretreatment with atropine (1 μmol/kg‐h) completely prevented the acid secretion induced by carbachol, but did not influence the secretion induced by histamine. Atropine had marked effects on the motor functions of the stomach, and seriously reduced the volume draining from the stomach. Infusion of phenol red indicated that the decrease in volume was due to a decrease in recovery of ingested water. SC‐15396, “antigastrin”, significantly depressed acid secretion induced by histamine, and reduced carbachol‐stimulated secretion, although the latter was statistically insignificant. The effects of SC‐15396 is discussed with reference to the absence of receptors for gastrin related to gastric acid secretion in t

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05997.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractA fatigue test consisting of repeated fast maximal contractions of the left quadriceps muscle in an isokinetic apparatus was performed by 12 healthy male subjects (19–25 yrs). EMG signals were recorded from the surface of the left vastus lateralis muscle, from which also biopsies were obtained for muscle fibre classification. Only minor changes were observed in the EMG variables despite a decrease in muscle strength performance, in terms of peak torque, work and power to about 50% of initial values after 100 contractions. The concomitantly obtained positive correlation between the increase in EMG/torque ratio and the individual percentage of fast twitch (FT) muscle fibres indicated that local factors in the muscle, primarily in the FT fibres, were causing the development of fatigue during repeated dynamic contractions with high power output

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05998.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractIsolated superfused field stimulated human omental arteries and veins, preincubated with3H‐(‐)‐nor‐adrenaline (NA) were used to study the frequency dependence of NA secretion and of the mechanisms for its local feedback control.3H‐NA secretion per shock was found to be basically a simple hyperbolic function of the stimulation frequency from 1 to 30 Hz, as long as secretion was restricted by prostaglandin E2(PGE2). In the absence of restriction, or during facilitation,3H‐NA secretion per shock reached its maximum at 10 Hz and then declined at 30 Hz, indicating ‘overload’ in some link in the secretory mechanism.3H‐NA secretion was depressed by exogenous NA and by PGE2, and enhanced by isoprenaline, phentolamine and by blockade of PGE2formation. Most of these effects were inversely related to the stimulation frequency. Attempts were made to study interactions between the different control mechanisms and to evaluate possiblein vivoconsequences of disturbance of adrenergic neuroeffector transmission by interference with the local control of the sec

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05999.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractSympathetic secretory responses from the parotid and the submaxillary glands of the rabbit were studied; sympathetic excitation occurred either alone or during a slow parasympathetic background secretion, imitating the resting secretion normally present. The fairly rapid sympathetically evoked flow of saliva from the parotid gland was, in the background secretion, further increased and obtained at low frequencies, which at sympathetic stimulation alone were subthreshold. The effects, which could be repeated with sympathomimetic drugs in a pilocarpine induced secretion, were abolished by αand βadrenoceptor blockade in combination. The submaxillary gland gave a very scanty secretion on sympathetic excitation, the effects being mediated via β‐adrenoceptors. The responses were not increased in a background secretion but the main effect of sympathetic activation was to retard the salivary flow. The retardation was attributed to vasoconstriction accompanying sympathetic excitation. Eliminating the vasoconstrictor responses, while retaining the sympathetic secretory effects, did not reveal any increase of the sympathetic salivary responses in the submaxillary g

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb06000.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe skin and colonic temperatures were recorded in frogs(Rana esculenta)which had selected a suitable microenvironment in a box filled with 2–3 cm water. The water temperatures ranged from 0°C to + 40°C. Such measurements were performed before and after intraperitoneal injections of killed pathogenic bacteria (M. xenopiandM. ranae), killed non‐pathogenic bacteria (M. aquae II) and 0.9% sterile saline, intraperitoneal injections of blood plasma from frogs pre‐injected with killedM. ranae, injections of PGE, into the brain. The injections of pathogenic bacterial endotoxin caused, after latencies of 5–120 min, higher preferred water temperatures, which produced an average maximum colonic temperature increase of 6.5°C ± 1.0°C (S.E.) (p<0.001). The non‐pathogenic bacteria and sterile saline caused no temperature change. Monophasic hyperthermia of shorter latency was caused by injections of blood plasma from frogs pre‐injected withM. ranae.Monophasic hyperthermia of the shortest latency was observed after diencephalic injections of PGE1. Based on their similarity we suggest that ectothermic and endothermic fever have a common phy

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb06001.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY