摘要:

AbstractCapillary permeability in skeletal muscle was investigated by applying the single injection, external registration method to the autoperfused cat gastrocnemius preparation.51Cr‐EDTA (MW: 341.2) and57Co‐B12 (MW: 1353.5) served as simultaneously injected indicators. At a plasma flow of 7 ml/100 g×min and an assumed capillary surface area, S, of 70 cma/g the permeability coefficients Pd(51Cr‐EDTA) and Pd(57Co‐B12) were 0.74 × 10‐5cm/s and 0.45×10‐6cm/s, respectively. However, correction for the recruitment of perfused capillaries yields Pd(51C‐EDTA)‐ 1.5 × 10‐5cm/s and Pd(57Co‐B12) = 0.9 × 10‐5cm/s. The results indicate that the permeability of a muscle capillary for hydrophilic solutes is similar to that of continuous capillaries in other tissues. The Pappenheimer pore radius estimate of 30 Å, the Karnovsky 40 Å interendothelial slit width, and pinocytotic transport are defective in accounting for the results as51Cr‐EDTA and57Co‐B12 diffuse across the capillary membrane at rates proportional to their free diffusion coefficients in water (CDC(51Cr‐EDTA)/CDC(57Co‐B12) = D(51Cr‐EDTA)/D(57Co‐B12)= 1.79). The intraendothelial patent channel system of fused vesicles might be the pathway for transcapillary exchange of hydrophilic molecules as this system alone could account for the experimental results. Only 1–2 open channels per μm capillary length are necessary to account for the observed permeabilities. For both indicators CDC was a linear function of plasma flow and CDC increased 3‐3.5 fold when plasma flow increased from 4 to 52 ml/100 g× min. Assuming constant permeability coefficients, the CDC increase with plasma flow reflects an increase in capillary surface area indicating a 3‐3.5 fold recruitment of capillaries. A constant ratio of CDC(51Cr‐EDTA)/CDC(57Co‐B12) within the perfusion range indicates that51Cr‐EDTA and57Co‐B12 can be employed at plasma flow>4 ml/100 g× min without risk of early ba

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05977.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe effect of indomethacin in hemorrhagic hypotension (HH) on total renal blood flow (RBF) and cortical flow distribution was studied in 9 pentobarbital anesthesized dogs. Local blood flow was measured as hydrogen clearance by 6 platinum electrodes in outer and inner cortex. RBF was recorded by electromagnetic flowmeter. Injection of indomethacin (3–5 mg/kg b.wt.) to inhibit prostaglandin synthesis, reduced renal blood flow only a few percent in control period. After the pretreatment with indomethacin, bleeding to mean arterial pressure 50 mmHg decreased RBF abruptly to 25% of control flow. Thus a renal vasoconstriction is observed both in early and late periods of bleeding in contrast to the initial vasodilation observed during the first half an hour of HH when prostaglandin formation was not blocked. Local blood flow in outer cortex decreased proportionally to flow in inner cortex during bleeding in both the indomethacin treated as in the untreated group, indicating an equal vasodilatory effect of prostaglandin in all parts of renal cortex during early periods of H

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05978.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractAn increased formation of a radioactive methylthiamine‐like substance (MTLS) in the end plate region of the rat diaphragm muscle and a release of radioactivity chromatographed as thiamine into the bath medium after a subcutaneous injection of35S‐thiamine were found after stimulation of the phrenic nerve. There was also an increased formation of the radioactive methylthiamine‐like substance in the denervated diaphragm preparation incubated with radioactive acetylcholine (ACh) in comparison with the innervated diap

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05979.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe turnover rate constants for extravascular albumin and immunoglobulin‐G (IgG) and the turnover rates and extravascular spaces for the proteins and regional blood flow were determined in different tissues in unanesthetized rabbits. The turnover rate constant in percent per minute for extravascular albumin was 1.9 in the kidney cortex and 1.4 in the kidney medulla, about 0.8‐1.4 in the lung, small intestine, choroid plexus and heart muscle and about 0.2‐0.6 in the skeletal muscle, stomach wall and gall bladder. The turnover rate constants for IgG were similar or lower. The plasma equivalent extravascular albumin space was 145 μl/g in the kidney medulla, about 100 μ1/g in the gall bladder, heart muscle, choroid plexus and small intestine, 30–70 μl/g in the kidney cortex, lung, stomach wall and triceps muscle. The extravascular IgG spaces were similar or smaller. In the liver, spleen and adrenals where extravascular spaces could not be determined, the ratios total IgG space/total albumin space were about 1.3‐1.5. Extraction of albumin defined as turnover rate of extravascular albumin/regional plasma flow could not be determined in the liver, spleen and adrenals. It was zero in the brain cortex, about 0.001 % in the lung and around 0.01‐0.05 % in most other tissues. The results suggest that in the walls of the capillaries of the kidney cortex, stomach wall, skeletal muscle and gall bladder there was convection of the proteins with pinocytosis and/or through large pores, diffusion playing little role. The albumin and the IgG passed through the tissues and were drained essentially by bulk flow. In the heart muscle, choroid plexus, lung and small intestine there seemed to be some diffusion of albumin through the capillary wall in addition to convection. Accumulation of IgG in the liver, spleen and adrenals was probably caused by adsorption to cells belong

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05980.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractIn 30 healthy subjects aged 20–48 years the hemodynamic response to carotid sinus stimulation (neck suction ‐40 mmHg) was studied. Heart rate, arterial pressure and cardiac output (dye dilution technique) were measured. In order to evaluate the effect of age on carotid sinus function the material was subdivided into two arbitrary subgroups, aged up to 30 years (n = 15) respectively 30 years and above (n = 15). Carotid sinus stimulation induced a significantly greater reduction in mean arterial pressure in the younger group compared to the older group. The heart rate reduction was, on the average, slightly greater in the younger group though the difference was not significant. In both groups a significant decrease in cardiac output contributed to the demonstrated reduction in mean arterial pressure. As the decrease in cardiac output was, on the average, slightly smaller in the younger group, the results indicate that the greater blood pressure response in the younger group was due to a greater reduction in peripheral vascular resistance. This is further supported by the finding of a significant correlation between changes in total peripheral vascular resistance, elicited by carotid sinus stimulation and

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05981.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractIn ten healthy subjects (mean age 29.6 years) the hemodynamic response to carotid sinus stimulation (neck suction ‐ 40 mmHg) was studied under control conditions and during peripheral pooling of blood (lower body negative pressure). Heart rate, arterial and central venous pressure, cardiac output and forearm blood flow were measured. The time sequence of the heart rate response was studied separately in six healthy subjects. During control conditions, carotid sinus stimulation induced a significant decrease in arterial pressure and heart rate. The blood pressure decrease mainly reflected a reduction in cardiac output, total peripheral vascular resistance being essentially unchanged. However, in the skeletal muscle, represented by a forearm segment, vascular resistance decreased significantly. During lower body negative pressure (LBNP) the same stimulation of the carotid sinus induced a significantly greater fall in mean arterial pressure even though the reduction in cardiac output was slightly smaller on the average than in the control condition. The heart rate increased, probably secondary to a time dependent increase in heart rate elicited by the continuous LBNP stimulus. Total peripheral vascular resistance decreased significantly during LBNP, the reaction likewise differing significantly from that in the control condition. Thus the augmented blood pressure response was due to a more pronounced vasodilatation when the carotid sinus was stimulated during lower body negative pressure. The results indicate that the hemodynamic changes elicited by carotid sinus stimulation are modified by changes in the distribution of blood volume and in the tone of resistance vessel

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05982.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractAfter extirpation of the pelvic ganglia the choline acetyltransferase activity decreased markedly indicating that most of the postganglionic cholinergic neurones of the bladder take this route. A small decrease in the activity of this enzyme was found after section of the hypogastric nerves, showing that these nerves contribute to some extent to the cholinergic innervation. The residual enzyme activity found after a combination of the two surgical procedures suggests that neurones relay distal to the level of the section of the hypogastric nerves and pass outside the pelvic ganglia and (or) that neurones pass the pelvic ganglia and relay distal to them. Electrical stimulation of the hypogastric nerves after extirpation of the pelvic ganglia and the use of blocking drugs showed on the existence of cholinergic neurones passing outside the pelvic ganglia, some of them relaying distal to the point of stimulation.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05983.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractIt has recently been suggested that adenosine is a metabolic coupling factor responsible for an increased cerebral blood flow during hypoxia or increased functional activity. However, tissue adenosine concentrations have been reported to increase in situations previously shown to be unassociated with changes in tissue AMP concentrations. The present experiments were undertaken to assess cerebral cortex concentrations of adenosine under normal circumstances, and to relate changes in adenosine, AMP and cyclic AMP during shortlasting ischemia. Following freezing and extraction of tissue, adenosine was measured using high pressure liquid chromatography. In paralyzed and anaesthetized (70% N2O) rats, freezing of tissue through intact skull bone gave an adenosine concentration of 0.9 ± 0.1 μmol·kg‐1(mean±S.E.M). With freezing through the exposed dura the concentration was 3 times as high with a large scatter. When special precautions were taken to avoid tissue trauma during craniotomy, the adenosine concentration was 1.1 ± 0.1 μmol·kg‐1. It is concluded that previously reported values are erroneously high. During the first 60 s of total ischemia there was a linear correlation between increase in AMP and in adenosine concentration (as well as between adenosine and cyclic AMP concentrations). It is concluded that increases in tissue adenosine concentration only occur if AMP accumulates. However, since (relative) changes in adenosine concentrations are at least twice those of AMP, analyses of adenosine may provide sensitive measures of a change in phosphoryla

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05984.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractTranscapillary passage of plasma proteins is enhanced in man's primary hypertension and it is debated whether this reflects increased permeability or merely a raised capillary pressure. To elucidate this problem, maximally vasodilated hindquarters of spontaneously hypertensive rats (SHR) and normotensive controls (NCR) were perfused in parallel at constant flow with dextran, horse serum or mixtures of the two, using labelled albumin as indicator of capillary permeability to macromolecules. By equal increases of venous pressure modest filtration was maintained during one hour, after which the edema and its albumin content were determined. — There was less edema in SHR, reflecting a slightly lower postcapillary resistance and a much higher precapillary resistance compared with NCR, which here resulted in a lower capillary pressure in SHR. In both SHR and NCR the presence of dextran slightly enhanced the capillary filtration coefficient but increased albumin permeability up to tenfold, also after antihistamine drugs. However, for each perfusate the SHR capillaries were, if anything, slightly less permeable to albumin than the NCR ones. — The results suggest that the enhanced transcapillary passage of plasma proteins in primary hypertension reflects an increased capillary pressure in some circuit(s), probably mainly skeletal muscle, resulting from the functional balancein vivobetween the pre‐ and postcapillary resist

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05985.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractIsolated hindquarters of rats were perfused at constant flow with a plasma substitute so that pressor responses to various concentrations of noradrenaline (NA) could be measured in consecutive sections of the vascular bed with normal (>1.5 mM) or low (0.2 mM) Ca2+in the perfusate. The animals used were 6‐week‐old spontaneously hypertensive rats of the Okamoto strain (SHRY), normotensive controls of the same age (NCRY); 6–7‐month‐old SHR (SHRA) and NCR (NCRA); and rats made hypertensive by clipping of one renal artery (RHR) plus matched normotensive controls (NCRB). Concentration‐response curves to NA showed that constrictor responses to NA become more dependent on external calcium as one proceeds peripherally in the vascular system in both SHRAand NCRA, with responses in proximal vessels being least and small pre‐and postcapillary vessels being most dependent in both cases. In low calcium SHRAretained their responses better than NCRA, whereas RHR retained their responses to NA poorer than did NCRB. No significant differences in responses in low calcium were observed in SHRTcompared to NCRYthough a trend in the same direction as in SHRAcould be traced. It is concluded that there is no evidence that altered handling of calcium initiates vascular hyperreactivity in SHR, but that the handling of vascular calcium in SHR differs from RHR and both di

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05986.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY