ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1995.tb09855.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Experiments were performed on chloralose anaesthetized cats. A 2‐cm segment of the proximal duodenum was isolated between two luminally situated balloons and perfused with isotonic saline containing [14C]‐PEG 4000 as a non‐absorbable marker. The perfusate was analysed with regard to alkalinity (back titration) and concentration of marker (liquid scintillation). Net alkalinization and net fluid transport were calculated with conventional equations. Motor activity in the duodenal wall was recorded as changes in volume of the proximal balloon. In presence of sympathetic neural activity (spontaneous or electrically stimulated) basal motor of sympathetic neural activity (spontaneous or electrically stimulated) basal motor activity and mucosal alkaline secretion was and increased minimally in response to luminal HCl (30 mM). Net fluid transport was in an absorptive state and shifted to a small secretion upon the acid‐exposure. Subsequent to bilateral acute splanchnicotomy, or the administration of the adrenolytic guanethidine (3–4 mg kg‐1, i. v.), spontaneous duodenal contractions occurred and the alkaline secretion was increased. Furthermore, both parameters were then markedly stimulated by luminal perfusion with 30 mM HCl. Basal net fluid transport was zero and turned into secretion upon the acid‐exposure. No morphological changes of the duodenal surface epithelium could be detected. The study demonstrates the existence of splanchnic nerve‐mediated, adrenergic inhibition of basal, as well as of acid‐induced duodenal motility, fluid and a

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1995.tb09856.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

To elucidate the specific function of the three phases (I‐III) of the migrating motor complex (MMC) by manometry, detailed analysis of individual pressure waves in the proximal duodenum was performed. Twenty healthy subjects (10 men and 10 women of whom 11 were tube‐naive) underwent computerized manometry for 5 h during fasting followed by 45 min after a meal using an 8‐channel water perfused catheter. Three recording points were in the antrum, three in the proximal duodenum (2 cm apart), one in the distal duodenum and one in the proximal jejunum. In all subjects at least one phase III (median 2) was observed during the 5‐h fasting recording. In the proximal duodenum the mean proportion of retrograde pressure waves, out of all propagating waves, was significantly increased in the last part of phase III (85 ± 9%, mean, SE), compared with early phase III (6 ± 5%), late phase II (5 ± 4%) and the feeding phase (10 ± 5%), irrespective of gender or previous tube‐experience. The median length of the MMCs was 108.5 min. There was no statistically significant difference between men and women or between tube‐naive and tube‐experienced subjects for the duodeno‐jejunal motility indices of phase II and phase III, nor for duration or migration of phase III. The postprandial motility index of the small intestine was increased compared with the interdigestive late phase II, particularly in the jejunum (P<0.02).The last part of the duodenal interdigestive phase III in healthy subjects shows the feature of a retroperistaltic pump. This cyclic sequence of retropropagation coincides with the reported rapid alkalinization of the duodenal bulb and the gastric antrum occurring in e

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1995.tb09857.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Electrical stimulation of the sympathetic innervation evoked secretion of submandibular and parotid saliva. By changing the mode of stimulation from a continuous to an intermittent one the fluid response increased and glandular blood flow improved. The volumes from the submandibular glands were larger than those from the parotid glands and further, the protein concentration of submandibular saliva was higher than that of parotid saliva. Adrenaline, isoprenaline and phenylephrine evoked larger fluid responses from submandibular than from parotid glands. However, the fluid response was small compared to the parasympathetic one. Substance P‐evoked saliva was used as carrier for protein released by sympathetic nerve stimulation or administration of adrenaline and isoprenaline.In vitrotissues of submandibular and parotid glands responded to adrenaline with a dose‐dependent release of protein. Taken together, the analytical pharmacology performedin vivoandin vitro, and including the antagonists phentolamine, dihydroergotamine, propranolol and metoprolol, showed that in submandibular glands, α(α1)adrenoceptors were predominantly involved in fluid secretion and β(β1)‐adrenoceptors predominantly involved in protein secretion. In parotid glands, fluid secretion seemed solely to depend on α(α1)‐adrenoceptors, while β(β1)‐adrenoceptors seemed almost solely involved in

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1995.tb09858.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Resting metabolic rate was measured in rats receiving single or double food portions every day or every other day, adding up to the same total food intakes. Starving rats were also measured. At two different total food intakes, there were no differences between the rats that were fed a meal every day and those fed a double meal every other day. Thus, the time interval between meals does not determine the extent of the metabolic depression. Also, the resting metabolic rates of rats fed various reduced food regimens are very similar to each other and to the resting metabolic rate of starved rats. The results of this study thus indicate that metabolic depression during starvation and severe caloric restriction in rats is an initially uniform response that modulates itself late in the starvation or restriction period in accordance with the total food intake.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1995.tb09859.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Intestinal permeability was determined in rats receiving colchicine 0.5 ± 0.15 mg day‐1in drinking water (30 mg L‐1) for periods up to 23 days. The lactulose/mannitol method was used to determine whole gut permeability before and on days 2, 4, 8, 18 and 23 of colchicine administration. The 8‐h urinary lactulose excretion following the test meal increased significantly in rats receiving colchicine, compared with the pretreatment value. Increased lactulose permeability was present after 2 days and remained stable throughout the experimental period. Mannitol urinary excretion was not changed. Colchicine increases intestinal tight junction permeability by an as yet undetermined mec

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1995.tb09860.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Although vasoactive intestinal peptide (VIP) is natriuretic it stimulates renin and aldosterone secretion. Therefore, to effect a natriuresis, VIP may need to modulate the sodium conserving actions of the renin angiotensin system (RAS) by another means. One possibility is that it alters the rate of disappearance from the circulation of one or more components of the RAS. We sought to determine whether VIP regulates the rate of catabolism of angiotensin II (Ang II). Steady state metabolic clearance studies of Ang II were undertaken with and without simultaneous VIP infusion. These studies were performed in rabbits on low, normal and high sodium diets, as dietary sodium has been shown to affect the metabolism of both VIP and Ang 11. The effects of VIP on plasma Ang 11 concentration and secretion were also studied. VIP decreased Ang II catabolism in rabbits on low (P<0.05) and normal sodium diets (P<0.05). Plasma levels of Ang II increased significantly in response to VIP in rabbits on these diets (low,P<0.04; normal,P<0.05). In contrast, in rabbits on a high sodium diet VIP increased the rate of catabolism of Ang II (P<0.001).Thus we conclude that the effect of VIP on sodium excretion may be modulated by its effects on Ang II metabolism. The decrease in Ang II catabolism seen in rabbit on low and normal sodium diets may prevent or ameliorate any natriuresis while the more rapid degradation of Ang II which occurs in dietary sodium excess may enhance the natriuretic effect of VIP.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1995.tb09861.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

In the present study we have compared the effects of increased intracellular Ca2+in whole frog skin and isolated epithelium (Rana temporaria). Cellular Ca2+was increased by the use of the endoplasmic reticulum Ca2+ATPase inhibitor, thapsigargin. Serosal addition of thapsigargin to the whole frog skin increased the Na+transport by increasing the apical Na+permeability. This could be blocked by the addition of indomethacin or by removal of Ca2+from the serosal solution. The increase in Na+transport was accompanied by an increased prostaglandin E2release. This indicated that the response in Na+transport was due to a Ca2+dependent activation of the prostaglandin E2synthesis. Addition of thapsigargin to isolated epithelia inhibited the Na+transport and had no effect on the prostaglandin E2release, though the prostaglandin E2release from the isolated epithelia could be increased by the addition of arachidonic acid. Addition of prostaglandin E2increased the cAMP contents of the isolated epithelia significantly, whereas thapsigargin had no significant effect on the cAMP level. Our results demonstrate that serosal addition of thapsigargin causes a release of prostaglandin E2from the dermis below the transporting epithelium. The prostaglandin E2diffuses to the epithelium where it activates the Na+transport by increasing cellular cAMP. The epithelium itself does not contribute significantly to the prostaglandin E2synthesis. Furthermore an increase in intracellular Ca2+in the epithelial cells without a concomitant increase in prostaglandin E2release leads to an inhibition of the active Na+‐transpor

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1995.tb09862.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Clearance and micropuncture experiments were performed in halothane anaesthetized rats. The aim was a comparison of paired estimates of glomerular filtration rate (GFR) from the renal clearance of [51Cr]EDTA (C[51Cr]EDTA) with simultaneous estimates of polyfructosan ((Inutest) CIn),3H,‐ and14C‐labelled inulin clearance (C[3H]Inand C[14C]In, respectively) and proximal tubular fluid/plasma concentration ratios (TF/P) of [15Cr]EDTA and TF/P ratios of14C‐labelled inulin measured in the same samples. C[51Cr]EDTAcorrelated well with, but underestimated CInby ˜ 10%. The correlation coefficient (r) was 0.92. C[51.Cr]EDTAalso correlated with, and underestimated C[14C]Inby 6%,r= 0.88, whereas it overestimated C[3H]Inby 5%, still with a close correlation (r= 0.92). Paired data on proximal (TF/P) ratios of [15Cr]EDTA and [14C]inulin were collected from early, mid and late proximal convolutions. The data were scattered around the line of identity,r= 0.91. It is concluded that [15Cr]EDTA is a valid alternative for estimates of total renal and single nephron GFR in rats and has the advantage of being less expensive than [14C]

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1995.tb09863.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Leg blood flow, blood pressure and metabolic responses were evaluated in six men during incremental one‐legged dynamic knee extension exercise tests (no load exercise ‐ 40 W); one performed with voluntary contractions (VOL) and one with electrically induced contractions (EMS). Pulmonary oxygen uptake was the same in both exercise modes, but the ventilatory coefficient was 2–5 L per L O2higher in EMS than VOL (P<0.05). Heart rate and mean arterial pressure were slightly higher with EMS than VOL at all exercise intensities reaching 138 (EMS) and 126 bpm (VOL), as well as 148 (EMS) and 137 mmHg (VOL) at 40 W, respectively (P<0.05). Leg blood flow, oxygen uptake and conductance were similar in the two exercise modes. At 40 W, mean muscle blood flow was close to 200 (range: 165–220) mL 100 g‐1min‐1, mean peak muscle oxygen uptake reached 230 mL kg‐1min‐1, and mean conductance became as high as around 45 mL min‐1mmHg‐1, and normalized for muscle size and arterial pressure it approached 100 mL min‐1100 g‐1100 mmHg‐1. Lactate and ammonia efflux from the leg were higher with EMS than with VOL and the difference became larger with increasing exercise intensity (P<0.05). Muscle glucose uptake was the same in each exercise mode. Femoral venous K+concentration increased with exercise intensity and was higher with EMS than with VOL, reaching 5.1 (EMS) and 4.7 mmol L‐1(VOL) at 40 W (P<0.05). The study demonstrates that electrically induced dynamic exercise is associated with a marked cardiovascular response similar to voluntarily performed exercise and a more pronounced activation of the anaerobic metabolism of the muscle. Furthermore, as the electrically activated muscle group is well defined, the present results confirm that peak muscle blood flow can re

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1995.tb09864.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY