摘要:

AbstractNaCl solutions were instilled into ligated unstimulated whole stomach pouches in cats for 30 min. On instillation of distilled water or 310 or 620 mM NaCl the net fluxes of NaCl were roughly proportional to the mean concentration difference between the gastric lumen and the blood. On instillation of more than 620 mM NaCl the absorption was larger than expected from this proportionality, a result believed to be due to an increase in the permeability of the gastric mucosa on instillation of such hyperosmotic solutions. Instillation of distilled water or 310 or 620 mM NaCl had only minor effects on the net flux of hydrogen ions out of the stomach during subsequent instillations of 170 mM HCl, In comparison with the controls. On instillation of HCI subsequent to an instillation of 620 mM NaCl the net fluxes of sodium ions and water into the stomach were significantly increased over the control level and there was a net influx of chloride ions instead of a net efflux. This result was probably due to secretion of a NaCl containing fluid. On instillation of 170 mRI HCl subsequent to an instillation of 930 or 1550 mM NaCl the net effluxes of hydrogen ions also were significantly increased over the control levels. The concentration of NaCl in the instilled solution needed to obtain an effect on the gastric mucosal ion permeability, both during the instillation of NaCl and on subsequent instillation of 170 mM HCl, was thus larger than 620 mM.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05557.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe reflex effects of distension and contraction of the gastric antrum on corpus‐fundus motility were studied in anesthetized cats. Besides a vagally mediated reflex corpus‐fundus relaxation, antral distension elicited a prompt reflex inhibition of corpus‐fundus contractions that was present also after vagotomy. In vagotomized animals this inhibitory reflex persisted also after cervical spinal cord transection, but was abolished by spinal anrsthesia or by guanethidine. Stepwise increases of antral distension revealed that the reflex corpus‐fundus inhibition appeared already at distending pressures of 5–10 cm H2O, then increased in a graded fashion and could be maintained for at least 10 min if a steady distension was applied. Also “isometric” antral contractions were effective in eliciting the reflex corpus‐fundus inhibition. — It is concluded that activation of slowly adapting “tension receptors” in the antral gastric wall inhibits gastric (corpus‐fundus) motilityviaa spinal reflex mechanism, mediated by splanchnic adrenergic fibres that seem to suppress the intramural excitatory cholinergic neurons. This gastro‐gastric adrenergic inhibitory reflex seems to be activated concomitantly with a vago‐vagal gastro‐gastric relaxatory reflex. It is suggested that these two suppressive reflex mechanisms play an important role in regulati

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05558.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe impulse response and the receptor potential 01 the isolated muscle spindle of the frog were recorded during sinusoidal stretching at frequencies from 0.1 c/s to 100 c/s. Attention was focused on the changes of the responses in the initial phase of stimulation before the steady state was reached. In the course of sine wave stimulation the impulse response of the spindle undergoes regular changes characterized by an increase in threshold and latency of the individual impulses, a decrease in phase lead and peak frequency and a reduction in number of spikes in each cycle. The changes are most pronounced during the first 2–5 cycles, and a steady state with a fixed impulse patterning is usually reached after 10–15 cycles. The receptor potential evoked by a sine wave stretch is distorted in comparison with the waveform of the stimulus in having a relatively faster rise and slower decay. With changes in frequency and amplitude of stimulation it undergoes characteristic alterations in phase lead and configuration. When superimposed upon a constant stretch or a linearly rising stretch, sinusoidal stimulation produces responses which increase in amplitude with the underlying stretch. These observations provide evidence that the sensory endings responsible for the transducer action do not obey linear transfer functi

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05559.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractAttempts were made to demonstrate an adaptive increase in glucokinase in isolated perfused livers. Several physiological factors, such as insulin, hydrocortisone, high glucose and low fatty acid concentrations, which may have a regulatory effect on the adaptive processin vivowere tested. None of these were sufficient to bring about the adaptationin vitro. Glucokinase of livers from fasted rats and then perfused with either bicarbonate buffer, 100 % blood or with mixtures of these media were studied. The concentration of free fatty acids in the media was decreased by addition of insulin and elevated by anti‐insulin serum. These changes were not accompanied by change in glucokinase activity. A moderate decrease in glucokinase in livers from carbohydrate fed rats was observed when the livers were perfused for several hours with subphysiological glucose concentration in the medium. The enzyme was quite stable, however, when glucagon was added to the system. The adaptive increase in glucokinase activity could be demonstrated if the fasted rats were refed a carbohydrate diet for 3 hours before the livers were excised. However, addition of insulin to the perfusion medium was not necessary. When the protein synthesis inhibitor cyclohemixide was added to the perfusion system, the glucokinase from carbohydrate fed liver was quite stable whereas the enzyme in standard diet fed rat livers decreased significantly within 6 hours from the start of the perfusion. This indicates a different turnover rate of the enzyme under different physiological condition

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05560.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe metabolism of parenterally administered14C‐histamine was studied in the toad (B. bufo), the terrapin (P. scripta) and the tortoise (T. hermanni). Paper chromatography and isotope dilution techniques were used for estimation of14C‐rnetabolites in urine. Urinary excretion of radioactivity usually exceeded 50 % of the total dose within 24–48 h of administration of14C‐histamine. Methylation of histamine to 1.4‐methylhistamine and further oxidation to 1.4‐methylimidazoleacetic acid was quantitatively the most important pathway for histamine degradation, accounting for about 80 and 50%of the radioactivity in urine of the toad and the reptiles, respectively. Oxidative deamination of histamine to imidazoleacetic acid also took place in all the studied species. In toad urine imidazoleecetic acid was found in the free form only, whereas in urine from both reptilian species most of it was boun

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05561.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractEarlier studies on human essential hypertension, as well as on SHR, suggest that an increased media thickness, partly encroaching upon the vascular lumen, forms the main background of the increased flow resistance in primary hypertension (e.g. Folkowet al. 1970). In the present investigation a comparison was made concerning the distensibility of the resistance vessels in order to further explore the proposed difference in vascular design. The simultaneously perfused hindquarter vessels of SHR and NCR were exposed to sudden, repeated shifts of pressure and flow, first at maximal vasodilatation and then at stable levels of smooth muscle tone, induced by barium ions or noradrenaline. Relative changes of vascular internal radius (ri) were calculated from the pressure‐flow values, assuming rito be proportional to4flow conductance. For given changes in distending pressure (Pd), the SHR resistance vessels exhibited considerably smaller percentual richanges than the NCR ones, whether starting from the same Pd, the same ri, or even when both Pd and riwere initially kept identical in NCR and SHR by exposing the SHR vessels to lower concentrations of constrictor agents. This evidence of reduced vascular distensibility in SHR was obvious both at maximal dilation and, particularly, when smooth muscle tone was increased. This strongly supports the view that especially the media component of the SHR resistance vessels is enhanced in bulk, thus markedly influencing both “active” and “passive” resistanc

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05562.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractNormal rats treated withL‐α‐methyldopa (400 mg/kg i.p.) after inhibition of the peripheralL‐DOPA decarboxylase by α‐methyldopa hydrazine excreted significantly less noradrenaline in the urine. The adrenaline excretion was only insignificantly reduced. The results indicate that treatment with a‐methyldopa can inhibit the release of noradrenaline from the sympathetic nerves by decreasing the impulse flow from the central nervous system. The adrenal medulla is influenced to a sma

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05563.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractAfter 5–10 h exposure in static bio‐assays first‐summerSalmo salarlive in equilibrium with the ambient ethanol concentration of 117 mmol/1 at 10° and 16° C. At 4° C this equilibration is retarded and is not evident until after 24 h. A quantitative connection between ethanol oxidation (M) and body weight (W) in accordance with the general formula M = K × Wbseems to exist for young salmon at 16° C. From the present tests the numerical values of the constants K and b were estimated to be approximately 10.5 and ‐1.03 respectively. Changes in behaviour induced by ethanol and the influence of temperature upon the metabolism of ethanol are discu

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05564.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe distribution of22Na within the villous tissue was studied by means if an autoradiographic technique during absorption of different saline solutions containing the tracer, the resolving power being about 10 μm. After the first minute of absorption most of the grains were localized in the epithelial cells, the grain density in the lamina propria being low. The same distribution of22Na was seen after 5 min incubatlon during maximal vasodilatation and during absorption of a hypotonic saline solution. On the other hand, a constant intraluminal perfusion of isotonic saline for 30 min changed the autoradiographic picture, the highest radioactivity concentration now being found in the lamina propria. The gradient of grain density along the villous length was, however, not as marked as that reported by Haljamaeet al. (1973), who proposed that this gradient was created by a countercurrent multiplication of sodium in the hairpin vascular loops in the villi. The results in this paper support the hypothesis that both sodium and water are crossdiffusing in such a system between the vessels constituting the countercurrent exchanger

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05565.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractPGE1and PGE2reversibly and dose‐dependently inhibited transmitter release from the stimulated guinea pig vas deferens. The two compounds proved equiactive and more prone to inhibit transmitter release at a low than at a high stimulation frequency. The PGEs inhibited the twitch response but produced inconsistent effects on contractions induced by prolonged stimulation. The difference may be due to the fact that the PGEs reduce the excitatory junction potentials and depolarize the effector cell membrane. Phenoxybenzamine increased transmitter release in response to nerve stimulation but failed to significantly alter the inhibitory effect of PGE2. It is therefore concluded that PGEs and presumed presynoptic α‐receptors probably intrude upon different levels of the process of excitation secretor, coupling. A possible model for the action of locally formed PGEs on the neuromuscular transmission of the vas deferens is adva

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05566.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY