摘要:

Ionized (saliva‐Ca2+) and total calcium (saliva‐CaT), inorganic phosphate (saliva‐P), magnesium (saliva‐Mg), and zinc (saliva‐Zn) levels in parotid saliva were studied in eight healthy volunteers during a 3‐h calcium infusion, directly regulated to obtain a pre‐settled standardized blood calcium level. Frequent determinations of whole blood ionized calcium (B‐Ca2+) were used for continuous adjustments of the calcium infusion rate (‘calcium clamp’). Basal B‐Ca2+(1.26 ± 0.04 mmol.l‐1, mean ± SD) was thus elevated to and maintained at 1.51 ± 0.05 mmol.l‐1from + 30 to + 180 min. Saliva samples were taken prior to the infusion and at regular intervals during the infusion period. Saliva‐Ca2+decreased from 0.38 ± 0.06 to 0.33 ± 0.05 mmol.l‐1(P<0.01) and saliva‐Ca2+as a percentage of saliva CaTfrom 63 ± 7% to 53 ± 10% (P<0.001) during the infusion. No changes could be observed in saliva‐CaT, saliva‐P, saliva‐Mg, saliva‐Zn, saliva‐Na and saliva‐K. Possible mechanisms behind these findings might be decreased parathyroid hormon

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07624.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

A new method for measuring oxygen consumption in monolayer cell cultures is described. Cells are cultured in shallow microchambers etched in glass chips. A haemoglobin solution is added and the microchambers are sealed airtight, the oxygenated haemoglobin solution serving as an indicator of oxygen tension within the microchamber as well as a source of oxygen. With cellular extraction of oxygen, an increasing amount of reduced haemoglobin is formed within the microchamber resulting in an increased absorbance of the haemoglobin solution at 435 nm. With a specially prepared device, it is possible to record this absorbance change with an ordinary laboratory spectrophotometer and, from this recording, it is possible to calculate the respiratory rate, provided the number of cells (or any other quantity of biological material), microchamber volume and haemoglobin concentration are known. Repeated measurements on the same undisturbed culture is possible. The system was tested on monolayer cultures of endothelial cells from the rat pulmonary artery.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07625.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

A standardized stenosis was induced by applying a silver clip around the left renal artery in male rats. This resulted in arterial hypertension within 10 days (as determined by increase in heart weight). Ornithine decarboxylase (ODC) activity was determined in the right (untouched) kidney, the left kidney, and the adrenal glands 1 day, 10 days, and 3 months after the operation. There was no difference in ODC activity in the right kidney of the operated animals when compared with matched controls. In the left kidney (with artery stenosis), ODC activity decreased to 40% after 1 day. A partial recovery was seen after 10 days (ODC activity 70% of normal), and after 3 months ODC activity had normalized. Removal of the clip 1 day prior to killing induced in the 3‐month group a more than two‐fold increase in ODC activity in the previously clipped kidney; ODC activity in the contralateral kidney was not affected. Only minor changes in ODC activity occurred in the adrenal glands following the operation. Contents of putrescine and spermidine were increased in the left (stenotic) kidney, and after clip removal, also in the right (untouched) kidney. Our observations thus indicate that alterations in renal blood flow are rapidly followed by changes in ODC activity. Contents of putrescine, spermidine and spermine seemed to a great extent to be independent of the ODC activ

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07626.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

From 20 women undergoing hysterectomy, strip preparations were isolated from the outer, longitudinal and the inner, circular smooth muscle layer of the ampullary‐isthmic junction (AIJ), together with small arterial segments dissected as ring preparations from the root of the mesosalpinx. The specimens were mounted in organ baths and isometric tension was recorded. In addition, tissue concentrations of substance P (SP) in the ampulla, AIJ and utero‐tubal junction were determined by radioimmunoassay. Tissue concentrations of SP expressed as pmol.g tissue‐1(wet weight, ± SE) amounted to 3.09 ± 1.40 in the utero‐tubal junction, 1.08 ± 0.299 in the AIJ and 0.742 ± 0.299 in the ampulla. In strips of circular muscle, SP at concentrations of 10‐7‐3 times 10‐6mol.l‐1elicited a combined phasic and tonic response and in longitudinal muscle a mainly tonic contraction was produced. In both tissues, contractions elicited by SP were rapidly abolished in calcium‐free medium. Nifedipine abolished the phasic contraction elicited in circular muscle by SP while the tonic response was resistant. The contraction in longitudinal muscle was reduced by 20–30%. Vasoactive intestinal polypeptide (VIP) decreased tension in preparations contracted by SP, prostaglandin F2αand K+‐depolarization (124 mmol.l‐1). In unstimulated oviductal arterial preparations, SP had no effect, while the peptide induced a transient relaxation of noradrenaline contracted preparations, and slightly decreased tension of K+‐depolarized vessels. The results suggest that SP may be involved in the contro

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07627.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The effects of cholecystokinin (CCK) and gastrin on proximal and distal colonic motility were investigated because of the possible role of these peptides in feeding‐induced colonic motility. Experiments were performed using 22 chloralose‐urethane anaesthetized cats in which the colon was acutely denervated. The volume changes of the proximal and distal colon were recorded with water‐filled flaccid balloons. The venous effluxes from the proximal and distal colon were recorded separately using drop recorder units. CCK‐8, 1–200 pmol. min‐1close i.a., and pentagastrin, 1–200 pmol. min‐1close i.a., evoked dose‐dependent contractions of the colon without altering systemic arterial blood pressure and colonic blood flow. The CCK peptides ‐8, ‐33 and ‐39 produced contractions of similar magnitude in the proximal and distal colon. The stimulatory effect of CCK‐8 and pentagastrin on colonic motility was blocked by tetrodotoxin (1 μg. kg‐1i.a.) and hexamethonium (10 mg. kg‐1i.v.). Atropine (0.5 mg. kg‐1i.v.) completely blocked the responses to CCK‐8 and pentagastrin in the distal colon but only partially in the proximal colon. Additional administration of naloxone (1 mg. kg‐1i.a.) abolished the remaining contractile response to the peptides in the proximal colon. The present results support the idea that CCK and pentagastrin have a stimulatory effect on distal colonic motility mediated via preganglionic and postganglionic cholinergic pathways. The possible role of opioid peptides and cholinergic mechanism

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07628.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The influence of theophylline and the related drug caffeine on the mechanical performance of fatigued muscle fibre isolated from semitendinosus muscle ofRana temporaria(2.5–6.7 °C) was investigated. The fibre was stimulated supramaximally to produce 1 s fused tetani and 2 s and 10 s partially fused tetani at intervals of 10 min. Fatigue was produced by shortening the contraction interval to 15 and 30 s. This caused a 15–20% decline in the maximum tension during fused tetanus and a 40–50% decline during partially fused tetanus. Theophylline and caffeine (0.1‐0.5 mM) did not change the maximum tension developed by the fatigued fibre during fused tetanization. Both drugs, however, markedly increased the tension output of the fatigued muscle fibre during partially fused tetanus. It was observed that the increase in partially fused tetanic tension by theophylline and caffeine was associated with an increase in the degree of fusion. This later effect was even more pronounced in the presence of diethyl‐stilboestrol. It is concluded that these drugs may not reverse the metabolic changes caused by fatigue, since they are unnable to increase fused tetanic force of a fatigued muscle fibre. The increase in partially fused tetanic tension of a fatigued muscle fibre by these drugs is probably due to enhancement of the activator calcium release from the sarcoplasmic reticulum in response to s

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07629.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The effect of sympathetic nervous activity on rectal motility induced by pelvic nerve stimulation (PNS) was studied in anaesthetized cats. Division of the sympathetic lumbar colonic and hypogastric nerves or alpha‐adrenoreceptor blockade, both of which reduced rectal tone, also reversed a predominantly relaxatory pelvic nerve response into a pure contraction. Contractions to pelvic nerve stimulation were reduced by simultaneous lumbar colonic nerve stimulation. This lumbar colonic nerve‐induced inhibition was augmented by alpha‐adrenoceptor blockade and abolished by beta‐blockade. Close intra‐arterial injection of a beta‐adrenergic agonist reduced contractions to PNS, while an alpha‐adrenergic agonist had no effect. Stimulation of the hypogastric nerves enhanced rectal contractions to simultaneous PNS. The apparent similarity with the arrangement of extrinsic nervous control of the internal anal sphincter suggests that the rectum is functionally involved in continen

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07630.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Plasma concentrations of free fatty acids (FFA), glycerol, adrenaline, noradrenaline, glucose and insulin, as well as serum concentrations of triacylglycerols, total cholesterol and high density lipoprotein (HDL)‐bound cholesterol, were measured at intervals during a 1‐year period in Norwegian reindeer. Free fatty acids and glycerol were high in January‐March, low in April‐July, and high again in August‐September. Glucose was low in November‐February and high but variable in March‐October. Triacylglycerols, total and HDL‐bound cholesterol were all low in November‐March, but increasing in April and reaching a peak in August‐September. Plasma noradrenaline and adrenaline did not change significantly throughout the year. Plasma insulin was low in October‐April, increasing significantly from June‐August/September. The seasonal changes in the serum concentrations of triacylglycerols, total and HDL‐bound cholesterol, as well as the plasma concentration of glucose, coincided with the seasonal changes in food intake. Free fatty acids and, to some extent, glycerol were, in contrast, inversely related to feed intake. It is suggested that insulin may play an important role in the long‐term regulation of fat mobilization, while the importance of catecholamines in t

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07631.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Addition of the K+‐channel blocking agent Ba2+to the basolateral solution (in a concentration which is assumed to block the K+‐flux via the K+‐channels completely) resulted initially in a two‐thirds reduction in the short‐circuit current (SCC), followed by a complete recovery of the SCC. To examine the reason for this recovery, experiments were carried out which made it possible to calculate the Na+‐permeability of the apical membrane (PaNa) and the K+‐permeability of the basolateral membrane (PbK). The presence of Ba2+had no significant effect on the cell volume and the cellular Na+‐ and K+‐concentration. Addition of Ba2+resulted in a depolarization of the intracellular potential (Vscc) from a control value of ‐ 76.3 ± 2.8 mV to ‐ 15.1 ± 1.7 mV. Although a complete recovery in the SCC was observed,Vsccdid not recover. The K+‐flux across the basolateral membrane was estimated from washout experiments. The washout of42K+(the K+‐efflux) could be described by a single exponential component with a half time of 30–70 min. The addition of Ba2+during the washout resulted in a transient decrease in42K+‐efflux from the epithelium. FromVsccand the cellular K+and Na+‐concentration and the coupling ratio of the Na‐K pump, it was found that Na+‐permeability of the apical membrane was 6.5.10‐7cm.s‐1before the addition of Ba2+and 1.7.10‐6cm.s‐1when the SCC had recovered after the addition of Ba2+andPbKchanged from 8.8.10‐6cm.s‐1to 1.5.10‐6cm.s‐1. Thus, the observed recovery in SCC was due to a considerable increase in Na+‐permeability of the apical membrane and the presence or appearance of a small Ba2+

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07632.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

To study the role played by Na, K‐ATPase in the pancreatic secretion of NaHCO3, experiments were performed in 20 anaesthetized, secretin‐infused pigs (3.0 clinical units.kg b. wt.·h‐1). The relationship between pancreatic NaHCO3secretion and arterial pH was obtained before and during Na, K‐ATPase inhibition by digitoxin and hypokalaemia. Na, K‐ATPase activity in pancreatic tissue homogenate averaged 5.45 (5.02–6.68) μmol Pi. mg. protein. h‐1. Retrograde injection of 0.5ml 1.4 times 10‐4mol.l‐1digitoxin into pancreatic ducts reduced pancreatic Na, K‐ATPase activity by 31(18–47)%, while intra‐arterial injection of 0.2 mg.kg b. wt‐1digitoxin reduced pancreatic Na, K‐ATPase activity by 50(45–56)%. Digitoxin and hypokalaemia reduced the rate of pancreatic NaHCO3and shifted the normal, proportional relationship between NaHCO3secretion and arterial pH towards higher pH. Hypokalaemia reduced Na, K‐ATPase activity and NaHCO3secretion in proportion. These effects indicate that Na, K‐ATPase helps to sustain the requisite electrochemical potential gradients for driving H+ions, and henc

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1985.tb07633.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY