摘要:

Combining an isogravimetric technique and a colorimetric ‘on‐line’ method (Rippe&Stage 1978). filtration capacity (CFC) and diffusion capacity (PS) were simultaneously measured in the maximally vasodilated fenestrated capillary bed of isolated, artificially perfused pancreatic glands in 12 juvenile pigs. Both CFC and PS for Cr‐EDTA were about 20 times greater than in the ‘continuous’ capillary bed of skeletal muscle. With perfusate flow rates of 250 ml/min × 100 g during isogravimetry, PS‐Cr‐EDTA averaged 110± 10.0 (S.E.) ml/min ±100 g, and diffusion limitation occurred first at flow rates above 300 ml/min ± 100 g. CFC was independent of flow rate and averaged 0.641+0.027 ml/minx 100 g ± mmHg. The parallel augmentation of PS‐Cr‐EDTA and CFC in the fenestrated capillary bed compared with continuous ones seems to reflect both a higher number of capillaries per unit tissue and an increased number of ‘small pores’ per unit capillary surface, whilst the ‘large pore system’ appears to be similar. Following bradykinin or histamine infusion, results were similar to those for continuous capillaries (e.g. Rippe, Kamiya&Folkow 1978). Thus, without further vasodilatation CFC increased 3‐fold while PS‐Cr‐EDTA increased only some 25%, and subsequent isoprenaline infusion reversed these effects. Previous studies on continuous capillaries indicate that histamine‐type agents act by opening additional ‘large pores’ in the venular exchange sections (cf. Rippe&Grega 1978, Svensjo 1978). while P‐adrenergic agonists block this effect. The results further suggest that the fenestrae are not involved in these bradykinin‐histamine effects, but rather fun

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1982.tb06953.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The importance of prostaglandin (PG) compounds for renal function in the developing kidney was studied by comparing renal blood flow (RBF), glomerular filtration rate (GFR) and fractional sodium (Na) excretion in control lambs and lambs treated with a PG synthesis inhibitor, indomethacin. The lambs were 1–2 and 4–6 weeks old and they were studied either during hydropenia (HP) or volume expansion (VE). lndomethacin significantly decreased Na excretion in both groups of hydropenic lambs. lndomethacin also completely blunted the natriuretic response to VE in the older lambs but had no effect on Na excretion in the volume expanded younger lambs. It is concluded that partial lack of PG inhibiting action on tubular Na transport will contribute to the poor natriuretic response to VE in neonatal lambs. Since PG will act locally rather than being blood‐borne messengers, the divergent PG action in younger and older lambs might be explained by local differences in maturation of PG metabolism as well as by local differences ir the maturation of PG sensit

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1982.tb06954.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

In normal rats lightly anesthetized with halothane apomorphine increased both resting and CO2‐‐dependent minute ventilation (VM) by stimulating respiratory frequency (RF) whereas tidal volume (VT) was slighly decreased. Acute bilateral glossopharyngectomy, which impaired carotid body function, did not change the apomorphine effects in contrast to bilateral vagotomy, which abolished the RF response of the drug, but now increased VT. Intravenous infusion of dopamine increased VM, by elevating RF, and this effect was only slightly blunted by bilateral glossopharyngectomy but nearly abolished by vagotomy and totally eliminated by the combined procedures. The respiratory response to dopamine was depressed in rats with chronically destroyed central catecholaminergic neurons. These findings indicate that there may be two different dopaminergic stimulatory mechanisms that modulate RF—one peripheral and one central—and both depend upon afferent vagal activity. With impaired vagal function, however, two other dopaminergic stimulatory mechanisms effecting V., are evident—one central, and one peripheral which involves the car

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1982.tb06955.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Calcium uptake by mitochondria and microsomes isolated from the human myometrum was studied at physiological Ca++concentrations. The initial rates as well as the maximum velocity of Ca uptake by mitochondria were 10–20 times higher than those by microsomes. The Ca++concentration for half‐maximal transport in the mitochondria and microsomes was about 1 μM and 0.5 μM, respectively. The Ca uptake capacity of mitochondria measured after 20 min of uptake (1 μM Ca++in the medium) was 10–30 times higher than that of microsomes. The capacity but not the initial rates of Ca uptake by microsomes was increased in the presence of 5 mM oxalate. There was only minor differences in the Ca uptake kinetics of subcellular fractions isolated from the pregnant and non‐pregnant myometria. The results of this study reinforce the argument for a domineering role of mitochondria in the relaxation of the human

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1982.tb06956.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

After acetazolamide administration, CO2hydration in pancreatic cells would be slow and might become a rate‐limiting factor to pancreatic HCO‐3secretion. Correspondingly, pancreatic HCO‐3secretion—normally pH dependent—would become slow and pH‐independent. However, acetazolamide would not be expected to interfere with the capacity of the secretory mechanism to generate a proton potential gradient between pancreatic cells and interstitial fluid. These predictions were examined in 5 anesthetized, secretin infused (2.7 C. U./kg b. wt. h‐1) pigs. Pancreatic juice was collected from a catheter in the pancreatic duct. Arterial pH was varied through i.v. HCI and NaHCO3infusions and CO3addition to inspired air. Before acetazolamide, HCO‐3secretion varied with plasma pH and averaged 298±30 μmol/min at control arterial pH. Acetazolamide (150 mg/kg, i.v.) reduced HCO‐3secretion to 84±12 μmol/min and rendered secretion independent of arterial pH between pH 7.6 and pH 7.0. It is concluded that acetazolamide imposes a pH‐independent transport maximum on pancreatic HCO‐3secretion, but does not reduce the capacity of the secretory mechanism to sustain a proton potential gradient between cel

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1982.tb06957.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Total respiratory exchange ratio (R) was compared to the respiratory exchange ratio over the legs (RQL) during exercise after different diets, to evaluate if R (which represents a mean for the whole body) can be used to estimate the relative proportions of fat and carbohydrate oxidation in exercising muscle. One important prerequisite for this is a steady state acid base balance. 7 subjects were studied at rest and during the later part of a 25 min exercise (65% of Vo2max) on two occasions, the first preceded by a fat rich diet and the second by a carbohydrate rich diet. Oxygen uptake, R and arterial‐femoral venous differences for [O2]. [CO2], PCO2and pH and arterial concentrations for lactate and β‐hydroxybutyrate were measured. Respiratory exchange ratio over the exercising legs (RQL) and ventilationloxygen uptake were calculated. Arterial pH, PCO2, lactate and β‐hydroxybutyrate as well as specific ventilation attained steady levels during the later part of exercise after both diets. Although arterial lactate and β‐hydroxybutyrate differed between the diets. the arterial pH and specific ventilation were the same. Both R and RQLwere higher after the carbohydrate than after the fat diet and there was no systematic difference between R and RQL. Therefore, it seems likely that R estimates the proportion of fat and carbohydrate oxidation in skeletal muscle during submaximal exercise after ext

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1982.tb06958.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The relative contribution of the splanchnic sympathetic innervation and the adrenal medulla for metabolism and hormone secretion during two different levels of hemorrhagic hypotension was investigated in 3 groups of anesthetized cats, viz. intact, adrenalectomized and splanchnicotomized (adrenalectomy + cutting of splanchnic nerves). In intact cats, hemorrhage caused very marked elevations of arterial plasma glucose, adrenaline, noradrenaline, dopamine, lactate, CAMP, glycerol and glucagon concentrations whereas plasma insulin fell to only 20% of control values. Adrenalectomy attenuated the glucose, adrenaline, noradrenaline and cAMP responses whereas the normal insulin inhibition was abolished. Splanchnicotomy further reduced the hemorrhagic glucose and glycerol responses and, possibly, also that of glucagon. It is concluded that the adrenergic system as a whole is important for the adjustments of the release of glucose, CAMP, glycerol, insulin and glucagon that occur during hemorrhage in cats. The adrenal medulla seems to be of particular importance for the regulation of cAMP release.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1982.tb06959.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

LINDBOM, L., TUMA, R. F.&ARFORS, K.‐E.: Blood flow in the rabbit tenuissimus muscle: Influence of preparative procedures for intravital microscopic observation. Acta Physiol Scand 1982,114:121–127. Received 21 April 1981. ISSN 0001–6772. Department of Experimental Medicine, Pharmacia AB, Uppsala, Sweden.The tenuissimus muscle in the rabbit and the cat is a suitable tissue for intravital microscopic investigation of skeletal muscle blood flow. In this study the influence of surgical procedures necessary for direct microscopic observation on the physiological state of the rabbit tenuissimus muscle was assessed by means of blood flow measurements. Mean resting blood flow was 2.8±0.8 (mean ± S.D.) ml. min‐1. 100 g‐1in the left tenuissimus muscle when prepared for microscopic observation as determined by the radioactive microsphere method. This value was not significantly different from that in the intact unexposed muscle in the contralateral leg, 3.3 ±1.1 ml. min‐1. 100 g‐1. Exposure of the muscle to atmospheric oxygen tension resulted in a reduction of blood flow to 0.7±0.4 ml. min‐l. 100g‐l, suggesting that local metabolic control mechanisms were active. The normal range of vascular control seemed to be maintained, as demonstrated by an increase in blood flow to 64.2± 18.8 ml. min‐1. 100 g‐lduring “maximal” vasodilation induced by topical application of PGE1. The tenuissimus muscle showed a marked sensitivity to mechanical stimulation. Slight stretching of the muscle, similar to what may occur during surgical preparation, resulted in an increase in blood flow to 17.5±5.7 ml. min‐1. 100 g‐1. Flow values calculated from data obtained by direct microscopic measurements in the tenuissimus muscle agreed well with those

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1982.tb06960.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

An in vivo tracheal muscle preparation in the rabbit was developed which enabled us to measure changes in the isometric tension of the trachealis muscle in response to electrical stimulation of autonomic nerves and to i.v. administration of autonomic agonists and antagonists. The preparation was very sensitive to injections of carbachol, and showed graded contractions to stimulation of the caudal end of the cut cervical vagus as frequency and strength of stimulation were increased. Stimulation of the rostral end of the cut cervical sympathetic nerve fibres produced contractions in all preparations. This effect was mimicked by the α‐adrenoceptor agonist, phenylephrine. The effects of both sympathetic stimulation and phenylephrine were blocked by phentolamine and not inhibited by pre‐treatment with atropine or propranolol. Sympathetic stimulation produced contraction of the trachealis muscle whether the initial tone was normal or actively increased by carbachol, while adrenaline produced relaxation when the initial tone was high. Using this new in vivo trachealis muscle preparation in the rabbit, we could show that sympathetic stimulation produced contractions of the trachealis muscle. This effect is consistent with the existence of smooth muscle activating alpha adrenocep

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1982.tb06961.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The individual response to overeating and semistarvation on energy expenditure at rest and light work before and after a test meal was investigated. This response was related to the change in dry body weight, measured as weight (W) minus total body water (TBW). Experiments were performed on 9 non‐obese subjects: (a) with a normal habitual energy intake; (b) (overfeeding) with an extra energy intake of 12 MJ per day for two weeks; and (c) (semistarving) with an energy intake of only 2.1 MJ per day for 2 weeks. Measurements of VO2, VCO2. W and TBW were obtained at the end of each of the three periods. It was found that the perturbation in energy intake from normal to 20–25 MJ per day increased the energy expenditure. The magnitude of this increase was highly individual and inversely related to the change in dry body weight. Energy expenditure, measured under the four standardized conditions, after 2 weeks of semistarvation was lower than that obtained after the preceding overeating period. This decrease was also roughly inversely related to the change in dry body weight. The results support the idea that part of the regulation of body energy content takes place by way of a change in the efficiency of energy utilization and that the response to a perturbed energy intake varies considerably between subje

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1982.tb06962.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY