ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1980.tb06621.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

We studied the effect of varying oxygen supply on the endocrine and exocrine secretions of the isolated perfused porcine pancreas utilizing completely synthetic perfusion medium with and without the addition of erythrocytes. With synthetic medium oxygenated to a Po2of 500 mmHg, oxygen consumption was constant for How rates at or above 0.5 ml×min‐1×g‐1(wet weight). Addition of erythrocytes to the medium did not increase oxygen consumption at flow rates above this level. Furthermore, the secretion of fluid, bicarbonate and protein in response to secretin and acetylcholine was not influenced by addition of erythrocytes. Similarly, the secretion of insulin, glucagon, pancreatic polypeptide, and somatostatin in response to arginine and acetylcholine was unchanged; arginine stimulated the secretion of all four peptides, whereas acetylcholine stimulated the secretion of insulin and pancreatic polypeptide and inhibited glucagon and somatostatin secretion. The results indicate that the porcine pancreas is respiring adequately, when perfused with a completely synthetic perfusion medium at flows above about 0.5 ml × min‐1× g‐1and Po2about 500 mmHg, and that addition of erythrocytes is not necessary for the study of its secretor

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1980.tb06558.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Shortening during activity of frog single muscle fibres caused a graded depression of the contractile force that persisted for 800–900 ms during a partially fused or completely fused tetanus. The depression of force was not associated with a change of the shortening velocity at zero load. Passive shortening performed just before stimulation had no effect on the subsequent course of contraction. The decrease in isometric force produced by shortening was not significantly affected by a stretch applied immediately before or after the shortening phase. For a given amount of shortening the depressant effect during a fused tetanus was 8–28% of that produced during a twitch. The effect was substantially reduced, both during twitch and tetanus, in the presence of 0.5 mM caffeine. The length dependence of the movement effect was studied between 1.7 and 2.9 μm sarcomere spacing. Maximum depression of force (in per cent of the control at each length) was obtained at 2.1–2.2 μm sarcomere length, the effect being steadily reduced at shorter and more extended lengths. The Q10of the depressant effect was 0.95±0.16 (S.D.). The features of the movement effect are consistent with a true deactivation of the contractile system as would occur if shortening reduced the binding of activator calcium to the regulatory proteins of the myof

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1980.tb06559.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

A gas pressure system is employed for topical application of pico/nanolitre volumes of 9 mmol/1 benzyl (14C) penicillin into guinea‐pig in vitro transverse hippocampal slices. Control of pressure pulse parameters enables ejectates, computed after liquid scintillation, from 10 μm, 5 μm and 2 μm pipettes with high reliability of ejection. A detailed study was done on the ejection performance of 5 μm and 2 μm pipettes. It shows that for the 5 μm tips, with the chosen ejection parameters, feeding pressure=0.5 MPa, feeding pulse duration 50 ms, a 99% ejection incidence was obtained (n= 200). The mean volumes ejected were 0.12 and 0.5 nl (n= 50) for one and four pulses delivered respectively. The corresponding ejectate means obtained from five 2 μm pipettes given a feeding pressure of 1.5 MPa, and a feeding pulse duration of 70 ms, were 0.04 and 0.13 nl. Statistical evaluation of the individual pipette ejection performances gave characteristic regression slopes within each pipette group. A comparison between visually controlled injection into oil and injection into slice, showed a close correspondence. The applicability of the ejection method is discussed in relation to functional studies on the conversion of single neurones into “epile

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1980.tb06560.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Cods were prepared for measurement of gastric acid secretion. Cannulae were implanted for drainage of the stomach and for separate perfusion of the stomach and intestine. Fishes, intestinally perfused with diluted sea‐water (33% SW) exhibited high rates of acid secretion. This “basal” secretion was abolished (96% inhibition) by bilateral vagotomy. Perfusion of the stomach with isosmotic glucose (5.5%) diminished the amount of titratable acid in the gastric effluence, and induced oral ingestion of water. Only part of the decrease could be explained by neutralization by ingested sea‐water. Perfusion of the intestine with 5.5% glucose, containing sea‐water to raise the osmolality to that of 50% SW, depressed gastric acid secretion compared to 50% SW‐perfused controls, without significantly affecting oral intake of water. I.m. administration of glucose, increasing plasma glucose to the same level as intraluminal administration, did not affect acid secretion or oral water ingestion. The study demonstrates the existence of a potential intestinal mechanism for inhibition of gastric acid secretion, and indicates that vagal activity is independent of the blood glucose level

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1980.tb06561.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

The effect of facial nerve stimulation on ocular blood flow was studied in rabbits. The intracranial part of the facial nerve was stimulated electrically and the regional blood flow was measured with labelled microspheres. Effects on the intraocular pressure were determined in a separate series of experiments. Stimulation increased choroidal blood flow by about 200%. The blood flow of the iris and the ciliary processes also increased. The blood flow of the eyelids and the nictitating membrane increased by approximately 1000%, and the blood flow of Harder's gland increased by about 200%. The blood flow of the tongue and the submandibular gland also increased. The increase in the uveal blood flow could not be abolished by a cholinergic or ganglionic blockade. Ganglionic blockade abolished most of the increase in the blood flow of the eyelids, nictitating membrane and Harder's gland; the cholinergic blockade seemed less effective. The intraocular pressure increased with a mean value of 6 mmHg during optimal (20–30 Hz) stimulation. The increase could not be prevented by cholinergic blockade. Much of the increase in uveal blood flow seemed to be caused by stimulation of unconventional nerves. It is suggested that these nerves may be peptidergic using VIP as a transmitter and lacking a hexamethonium sensitive synapse between the site of stimulation and the eye. Their nature—afferent or efferent—remains unknown. A great part of the increase in blood flow of the eyelids, nictitating membrane and Harder's gland seemed to be due to other mechanisms involving nerves with a peripheral sy

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1980.tb06562.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Light and electron microscopic studies have been performed on different parts of cod stomach. The studies have been concentrated on the gastric glands of the gastric mucosa. The glands consist of only one cell type. This cell contains an apically located, comprehensive tubular system as well as zymogen granules and therefore probably secretes both acid and zymogen. The high degree of development of certain organelles and their mutual localization shows a structural organization which appears suitable for an effective secretion. What appears to be intermediate organelle forms are common. When acid secretion is increased by continuous intramuscular infusion of histamine or of carbachol the most marked structural changes are increases in the size of the gland lumen and in the cell membrane facing the lumen. Histamine in particular causes the appearance of numerous long and slender cell processes in an enlarged gland lumen. When the acid secretion, increased by histamine, had reached a plateau, metiamide was infused. This histamine H2‐receptor antagonist caused a decrease in acid secretion as well as in the size of the gland cell surface to values characteristic of untreated co

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1980.tb06563.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Isolated rat lungs were perfused with homologous blood at constant volume inflow. The effect of ventilation hypoxia on pulmonary vascular resistance, preparation weight and reservoir volume (vascular capacitance) were studied. In some experiments also wet/dry weight ratio of the preparation was estimated (extravascular water content). There was no difference in this last parameter between hypoxic and normoxic lungs, thus alveolar hypoxia had no effect on tissue water content as previously described in intact rats. With forward perfusion small and transient changes in either direction were seen in preparation weight and reservoir volume, even though inflow pressure exceeded 5 kPa during alveolar hypoxia. With backward perfusion marked weight increases were seen, and if inflow pressure in this situation was above 3.5 kPa, the weight change was irreversible, thus indicating outward fluid filtration. It is concluded that the vessels responding to alveolar hypoxia are located on the arterial side of the pulmonary vasculature.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1980.tb06564.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

The stability of the nuclear chromatin in human spermatozoa soon after ejaculation was studied by exposing the cells to sodium dodecyl sulphate (SDS) one to 20 min after ejaculation. Semen samples were obtained both from men with apparently normal, and from men with impaired prostatic secretion (=subnormal seminal plasma [Zn]). The sperm nuclear resistance to decondensation in SDS increased in both groups during the first 15 min after ejaculation, but was significantly lower in the semen samples with subnormal [Zn]. This fast post‐ejaculatory increment in sperm SDS resistance was significantly reduced by a 5‐fold saline dilution of the semen at the time of ejaculation. It is discussed if the observed stabilization with time was illusory and that a prostatic component instead counteracted an intrinsic nuclear chromatin decondensation (NCD) process initiated by SDS derangement of spermatozoal membra

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1980.tb06565.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

In semen from donors with adequate secretory function of the prostate, spermatozoa in the first (“prostatic”) portion of the ejaculate were more resistant to nuclear swelling in sodium dodecyl sulphate (SDS) than spermatozoa from the second (“vesicular”) portion. No such difference was revealed by a donor with severely impaired prostatic function. This demonstrates that some sperm nuclear chromatin stabilizing factor(s) is present in normal prostatic fluid. The chromatin stabilizing factor(s) could largely be removed by washing the spermatozoa in saline containing albumin. Spermatozoa sensitized to SDS in this manner regained their SDS resistance upon exposure to normal (zinc‐rich) “prostatic fluid”. Such exposure also induced a high degree of resistance in natively SDS sensitive spermatozoa. The possibility is discussed that zinc of prostatic or other origin reversibly inhibits a nuclear chromatin decondensation ability (NCD‐ability). It is suggested that such a mechanism may be of essential importance for male

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1980.tb06566.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY