摘要:

The oxidation of14C‐labelled glucose, β‐hydroxybutyrate and palmitate to CO2and the incorporation of14C‐labelled amino acid into alkali‐soluble protein were studied in aorta from fed and fasted male Sprague‐Dawley rats, weighing about 200 g. Substrate oxidation and amino acid incorporation were measured during incubation of rat aorta in vitro for 2–3 h. After fasting for 6 h there was a slight but significant increase in the plasma concentration of β‐hydroxybutyrate. Blood glucose was lowered after 12 h while an increase in the plasma concentration of free fatty acids was found after 24 h. A decrease in the oxidation of glucose in rat aorta was found after fasting for 12 h and with prolonged fasting a further decrease in the aortic glucose oxidation was found. After fasting for 4 days the oxidation of β‐hydroxybutyrate and the incorporation of14C‐leucine and14C‐phenylalanine into protein were reduced in rat aorta while the oxidation of palmitate was not altered. The effects of fasting on substrate oxidation and amino acid incorporation in rat aorta, found in this study are similar to the known effects of diabetes

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1982.tb07095.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Body temperatures and oxygen consumption of three sub‐adult polar bears (Ursus maritimus) during treadmill exercise are presented. Comparisons are also made with results from prior studies of polar bear locomotion. The increase in body temperature and the metabolic cost were unexpectedly high, particularly in young animals. An equation describing the cost of locomotion versus body mass shows a negative, and apparently linear relationship. A significant correlation between body temperature and oxygen consumption may permit the use of body temperature telemetry to estimate activity metabolism of free‐ranging polar be

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1982.tb07096.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

In order to investigate the impact of molecular charge on capillary permeability to macro‐molecules, capillary reflection coefficients (a) for various concentrations of two neutral dextran fractions (M̄w 70 000 and 139 000) and one negatively charged, sulphate‐substituted dextran fraction (M̄w 109 000) were determined in the isolated perfused rat hindquarter preparation, during stable haemodynamic conditions. The capillary reflection coefficient was calculated as the ratio between the estimated colloid osmotic pressure in vivo, determined by an osmotic transient technique, and that in vitro, measured with an osmometer. Despite its intermediate size the sulphated dextran (D 109‐S) showed a markedly higherathan the two neutral ones (D 70 and D 139) and, further, whereas o for D 70 and D 139 decreased with increasing dextran concentration, o for D 109‐S remained constant over the whole range of concentrations investigated. At dextran concentrations equivalent to an in vivo colloid osmotic pressure of 23.5 mmHg, s̀ averaged 0.901 for D 109‐S, compared with 0.547 and 0.693 for D 70 and D 139, respectively, and with 0.87 for albumin in normal plasma. It is suggested that capillary macromolecular permeability is due to both structural and electrophysical properties of the microvascular barrier, where negative charges of the endothelial glycocalyx and of wall‐adsorbed plasma proteins cause repulsion of circulating lar

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1982.tb07097.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Isometric force and action potentials were recorded in rabbit papillary muscles. It was found that the monophasic decline of the contractile potentiation that was recorded after an extrasystole (ES) was replaced by transient mechanical alternans (TMA) when temperature and calcium concentration of the perfusion medium had been lowered (from 37° to 27°C and from 2.0 to 0.5 mM, respectively). TMA in response to ES was also seen when the preparation was exposed to 2 mM 4‐aminopyridine. Furthermore, TMA could be induced by a shortening step during activity. Mechanical restitution curves were recorded by relating max. rate of force development of a test contraction to the duration of the preceding stimulus interval. It was found that the alternating contractions during TMA were associated with shifts of the mechanical restitution curve along the force axis. The duration of the action potential was inversely related to force development during TMA. It is proposed that TMA is due to a reduced damping of a regulatory feedback system between inotropic state and intake of activator calcium during the action potential. The following sequence of events are suggested: The abbreviated action potential accompanying a potentiated contraction is associated with reduced intake of activator calcium. This leads to depression of the subsequent contraction. The latter contraction is associated with increased calcium intake due to prolongation of the action potential. This will lead to potentiation of the next beat and the sequence is repeated. It is proposed that recirculation of calcium between heart beats will act as a damping factor of this sys

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1982.tb07098.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

To determine the lowest continuous positive airway pressure (CPAP) at which breathing becomes regular and to determine whether the phrenic nerve activity changes simultaneously, breathing pattern and phrenic nerve activity were studied in spontaneously breathing newborn lambs at various levels of CPAP. A CPAP of 0.25 kPa decreased the variability of phrenic burst interval, i.e. made the breathing regular. This CPAP also increased the mean impulse frequency within the phrenic nerve bursts, indicating greater inspiratory activity. A high CPAP did not offer any further advantages to the breathing pattern or to the inspiratory activity.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1982.tb07099.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

6 healthy subjects were studied on 3 separate occasions after ingestion of an ordinary breakfast. Once the meal was given alone, once together with somatostatin infused i.v. (100μg/h) for the first 2 h after start of the meal, and once the meal was preceded by a 34‐h fasting period. The postprandial plasma PP secretion was completely inhibited during the somatostatin infusion, and significantly augmented (p=0.032) after the prolonged fast. During the 34‐h fasting period, the PP levels were almost unaffected. The same group of subjects were also studied during a “normal” day with 4 regular meals. Plasma PP was found to increase shortly after breakfast and did not return to basal levels before early the next morning. The integrated PP secretion during the 24‐h period showed a significant (p<0.003) correlation with the ba

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1982.tb07100.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Substance P‐immunoreactive nerve fibres were fairly numerous in the lower esophagus of the guinea‐pig and cat but few in the pig. They were particularly numerous in the myenteric and submucosal plexuses but could be detected also in the circular and longitudinal smooth muscle and in the muscularis mucosae. Only in the cat were SP‐immunoreactive cell bodies detected, albeit in low number, in the myenteric plexus. Radioimmunoassay showed that the lower part of the cat esophagus contained approximately 10 times more immunoreactive SP than the upper part and that the muscle layer contained more SP than the mucosa. Motor effects of synthetic SP were studied on segments from circular smooth muscle of cat esophagus. SP contracted the smooth muscle and enhanced the response to electrical stimulation. These effects of SP could be blocked by the specific SP antagonist (d‐Pro,2d‐Trp7,8)‐SP. The contractile response to electrical stimulation could be blocked by the cholinergic muscarinic blocker atropine and the opiate receptor agonist leu‐enkephalin but not by the SP antagonist or by adrenergic blockers. Hence, the results suggest that cholinergic neurons innervate the circular smooth muscle, and that opiate receptor agonists suppress transmission in these neurons. Neuronal SP in the esophagus may serve to enhance the contractile responses of esophageal

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1982.tb07101.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Substance P, a putative neurotransmitter in mammals, and physalaemin, present in the skin of an amphibian, are both undecapeptides and belong to the family of tachykinins. The secretory effect of these tachykinins on parotid and submaxillary glands of the rat was examined. Dose‐response curves showed that in the unoperated glands maximal secretory responses were obtained to an intravenous dose of 5–10μg/kg of the tachykinins, that the amount of saliva secreted from the submaxillary gland was twice that from the parotid gland, and that physalaemin was more potent than substance P. Parasympathetic denervation of the parotid gland and decentralization of the submaxillary gland caused a marked sensitization to the tachykinins, as judged by lowered threshold doses for secretion and increased secretory responses to a series of submaximal doses 3 weeks postoperatively. Sensitization was less marked after sympathetic denervation and decentralization; in the parotid gland decentralization caused, in fact, no sensitization while in the submaxillary gland the degree of sensitization was about the same after the two types of operation. The tachykinins acted directly on the gland cells and the effect was not exerted via cholinergic, α‐adrenergic or β‐adrenergic receptors. The pattern of sensitization to the tachykinins, found in the present study, after the different types of operation is similar to that previously found to cholinergic and α‐adrenergic agonists and different from that to a β‐adrenergic agonist. Studies by others have shown that in the rat parotid gland peptidergic receptors share a common intracellular pathway with cholinergic and α‐adrenergic receptors, whereas β‐adrenergic receptors use another pathway. In the present study it is suggested that this intracellular arrangement is of importance for the developme

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1982.tb07102.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The effect on net intestinal fluid absorption of unloading the baroreceptors by bilateral carotid occlusion was studied in rats and cats. It was shown that net fluid uptake from the intestine increased 30–40% upon carotid occlusion. This effect was eliminated by cutting the splanchnic nerves (cats) or by severing the nerves surrounding the superior mesenteric artery (rats). In fact, these denervation procedures resulted in a decreased net fluid absorption upon carotid occlusion. Cutting the vagal nerves did not significantly influence the response to carotid occlusion. It is concluded that the arterial baroreceptors influence net fluid transport in the small intestine, a reflex compensatory mechanism that may be important in different hypotensive situation

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1982.tb07103.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The mechanism of increased preload and its contribution to the rise in blood pressure during intravenous angiotensin infusion were studied in anesthetized dogs. In open‐chest dogs angiotensin increased mean aortic blood pressure by 58±12 mmHg. Left ventricular end‐diastolic dimension, measured as myocardial chord length (MCL) by ultrasonic technique, increased by 7±1 %. By inflating a balloon in the inferior vena cava, end‐diastolic MCL was reduced to control value and the rise in mean aortic blood pressure was almost halved to 32±10 mmHg above control value. A similar preload effect was recorded in closed‐chest dogs using end‐diastolic left ventricular pressure as an estimate of left ventricular volume. During angiotensin infusion to the upper body only, end‐diastolic MCL did not increase. When redistribution of the splanchnic blood volume was prevented, the effect of angiotensin on end‐diastolic MCL was reduced to 1/3. Angiotensin reduced liver but not splenic dimension measured by ultrasonic technique. We conclude that about half of the rise in blood pressure during angiotensin infusion is due to increased end‐diastolic volume caused by blood redistribution. About 2/3 of this increase in preload is due to redistribution from the splanchnic bed, mai

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1982.tb07104.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY