ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb07472.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Trunk movements in the frontal and sagittal planes were studied in 10 healthy males (18–35 yrs) during normal walking (1.0–2.5 m/s) and running (2.0–6.0 m/s) on a treadmill. Movements were recorded with a Selspot optoelectronic system. Directions, amplitudes and phase relationships to the stride cycle (defined by the leg movements) were analyzed for both linear and angular displacements. During one stride cycle the trunk displayed two oscillations in the vertical (mean net amplitude 2.5–9.5 cm) and horizontal, forward—backward directions (mean net amplitude 0.5–3 cm) and one oscillation in the lateral, side to side direction (mean net amplitude 2–6 cm). The magnitude and timing of the various oscillations varied in a different way with speed and mode of progression. Differences in amplitudes and timing of the movements at separate levels along the spine gave rise to angular oscillations with a similar periodicity as the linear displacements in both planes studied. The net angular trunk tilting in the frontal plane increased with speed from 3–10°. The net forward‐backward trunk inclination showed a small increase with speed up to 5° in fast running. The mean forward inclination of the trunk increased from 6° to about 13° with speed. Peak inclination to one side occurred during the support phase of the leg on the same side. Peak forward inclination was reached at the initiation of the support phase in walking, whereas in running the peak inclination was in the opposite direction at this point. The adaptations of trunk movements to speed and mode of progression could be related to changing mechanical conditions and different demands on equilibrium control due to e.g. changes in support phase durat

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb10452.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb07473.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Isometric force, glycogen phosphorylase activity and lactate production were measured under conditions known to alter intracellular Ca2+and cAMP to assess the role of these messengers in the coordination of metabolism with contractility in rat portal vein. Total phosphorylase (a+b) activity, was independent of treatment. The activity ratio phosphorylase activity ratio in the presence of isoproterenol and papaverine was dependent on or high‐K+medium, and 0.57 after 20 min treatment with 10–5M isoproterenol+10‐4M papaverine. Under both of these conditions the muscle was totally relaxed. The phosphorylase activity ratio in the presence of isoproterenol and papaverine was dependent on extracellular Ca2+, both in normal and depolarizing medium. This suggests a lower Ca2+sensitivity of the contractile than the phosphorylase system under these conditions, known to be associated with raised intracellular cAMP. During spontaneous activity and high‐K+induced contractures phosphorylase activity was increased compared to the relaxed state in Ca2+‐free medium. A high level of phosphorylase activity (0.48) was elicited by the addition of 300 mM sucrose, which induces a contracture in Ca2+‐free medium. Lactate production was in general parallel to phosphorylase activity, except for a relative increase in anoxia. The results suggest that in the intact cell the Ca2+‐mediated linkage of contraction and phosphorylase may be modified by cAMP changing the Ca2+sensitivities of the two systems in opposi

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb10453.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Blood samples were collected in peripheral venous blood of seven lactating sows, when their piglets were suckling. In four of the experiments samples were also taken when the sows were fed a meal. Gastrin, insulin, somatostatin and VIP levels were measured by radioimmunoassay. Insulin levels increased by—100% for about 10 min in response to suckling, in some experiments even before the suckling occurred, i.e. when the sows, saw, heard and smelt their piglets. In four of the sows suckling caused a biphasic twofold increase in gastrin levels—one immediate peak which lasted for a few min and a second peak of longer duration (about 30–60 min), whereas gastrin levels remained unchanged in three animals. Somatostatin levels usually reflected gastrin levels in a reciprocal way. Thus, a biphasic decrease of somatostatin levels occurred in the high gastrin responders. In contrast, somatostatin levels increased in the experiments, in which gastrin levels did not change. Immediate and short‐lasting (a few minutes long) increases of VIP levels were also induced by suckling. Large litters and long suckling periods appeared to be related to greater changes of the levels of all the peptides measured. Feeding influenced insulin, gastrin and somatostatin levels in the same way as did suckling from both a qualitative and a quantitative point of view. In contrast, VIP levels were not increased by feeding. The possible functional effects of the suckling‐induced release of gastrointestinal hormones and possible mechanisms of their release are

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb10454.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Bicarbonate secretion from 12 mm segments of duodenum just distal to the Brunner's gland area was titrated (pH 7.60) in situ in anesthetized rats. Intravenous BW755C (10–20 mg/kg) increased both bicarbonate secretion and the transmucosal electrical potential difference and pretreatment with indomethacin (3 mg/kg intravenously) prevented these effects. Indomethacin also inhibited stimulation of HCO3‐secretion by luminal acid (10 mM HCl) but had no effect on the rise in secretion in response to exogenous (luminal) prostaglandin E2. The results support previous suggestions of a role for endogenous prostaglandins in mediation of the HCO3‐response to acid and are consistent with the recent demonstration that BW755C increased prostaglandin formation in homogenates of rat intestinal mucosa. Stimulation of HCO3‐secretion by BW755C was not enhanced but attenuated by preexposure to luminal acid, suggesting that the latter increases secretion by effects other than mucosal mobilization of arach

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb10455.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

To examine the effects of pulmonary vascular pressures and flow on pulmonary blood volume (PBV), experiments were performed at constant heart rate and zone 3 conditions (mean left atrial pressure (LAP) above airway pressure) in six anesthetized, open‐chest dogs. PBV was calculated as the product of electromagnetic aortic flow and pulmonary mean transit time for ascorbate, obtained without blood withdrawal by polarographic recording of aortic ascorbate changes. In three series of experiments LAP was raised similarly in three steps, from 4.5 to 14.8 mmHg: by mitral constriction which reduced pulmonary blood flow, by blood volume expansion which more than doubled pulmonary blood flow, or by a combination of the two procedures which kept pulmonary blood flow constant. In all three series, LAP and mean pulmonary arterial pressure (PAP) rose in proportion, but PBV was better correlated to PAP (r=0.87±0.02) than to LAP (r=0.66±0.09). These experiments suggest that PAP is the most important factor in determining PBV under zone 3 conditions, whether PAP is raised by increasing pulmonary blood flow or by mitral constrict

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb10456.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The contribution to the extracellular fluid volume (ECV) from plasma volume (PV) and the total interstitial volumes contained in skin (IFVS) and skeletal muscle (IFVM) has been studied in rats over a wide range of overhydration and dehydration. ECV was measured as the two‐hour distribution space for51Cr‐EDTA after nephrectomy while PV was measured with radiolabelled albumin or erythrocytes. Total interstitial volumes in skin and skeletal muscle were calculated from measurement of local interstitial volumes and the amount of skin and skeletal muscle in the rat. In control conditions ECV was on average 24.12 ml/100 g body weight. PV was 11.0% of ECV in control while IFVS and IFVM was 28.1% and 19.0% respectively. In dehydration the change in PV was 13.3% of the change in ECV, while the change in IFVS and IFVM was 30.0% and 21.0% of the change in ECV respectively. In overhydration (ECV on average 33.76 ml/100 g rat) the changes in PV, IFVS and IFVM were 7.5%, 22.1% and 17.2% of the change in ECV respectively. The regression coefficients describing the change between ECV and IFVS and IFVM were not significantly different in overhydration and dehydration while the regression coefficient between ECV and PV in overhydration was significantly less than the regression coefficient in dehydration. Thus, the fraction of ECV contained in skin and skeletal muscle is similar over the range of hydration studied. The fraction of ECV located in plasma is similar in control and dehydration, while in overhydration less of ECV is localized in plasma. The observed distribution of ECV validates previous compliance measurements based on pressure measurements in skin together with measurements of total ECV. The present results support the hypothesis that regulation of the total extracellular volume can be accomplished through regulation of plasma volume alone without the need for volume receptors located in the interstit

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb10457.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb07474.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Effects of intraarterial prostacyclin (PGI2) infusions on interstitial hydrostatic and oncotic pressures and on the tubuloglomerular feedback (TGF) control of glomerular filtration rate (GFR) were studied in rat kidneys. The hilar lymph flow rate was used as a measure of interstitial hydrostatic pressure and the lymph protein concentration was used for interstitial oncotic pressure estimation. In the micropuncture experiments the stop‐flow pressure technique was employed for determining the TGF characteristics, i.e. stop‐flow pressure (PSF), maximal reduction of PSF(ΔPSF) and turning point (TP), defined as the end‐proximal flow rate at which 50% of ΔPSFwas obtained. Non‐hypotensive doses of PGI2(50 to 100 ng‐kg‐1B. W.‐min‐1) infused in 30 min evoked an increase in urine and lymph flow rates and a decrease in lymph protein concentration, but did not affect GFR. ΔPSFwas reduced (9.9±1.0 mmHg versus 4.7±2.2 mmHg) and TP increased (22±2 nl/min versus 34±2 nl/min), but the PSFwas unaffected. These changes were seen during the infusion period and during the immediate post‐infusion control period of 30 min. Our data indicate that non‐hypotensive doses of PGI2in some way can affect the renal interstitial pressure

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1984.tb10458.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY