ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08806.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08807.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Forty‐five minutes of warm ischaemia and 20 min of recirculation in the rat kidney was found to result in (1) a massive transient extravasation of plasma upon recirculation and (2) an increase in plasma‐lymph transport of proteins during the first hours after onset of circulation. This was accompanied by trapping of erythrocytes, as determined with51Cr‐labelIed erythrocytes, in the capillaries, mainly in the inner stripe of the outer medulla. At scanning electron microscopy of vibratome sections, the trapping appeared as aggregates of polygonally shaped erythrocytes. It is concluded that 45 min of ischaemia and 20 min of recirculation results in an increase in the permeability of the renal capillaries. This increase leads to extravasation of capillary plasma with consequent local haemoconcentration, causing an increase in vascular resistance and in capillary hydrostatic pressure. This elevated pressure will, in turn, lead to perpetuating extravasation of plasma, further haemoconcentration and so on, eventually resulting in dense packing of polygonal erythrocytes, obstructing the blood flow. It is believed that oxygen‐derived free radicals generated in the early recirculation phase contribute to the increase in macromolecular permeability, since the scavenger bovine superoxide dismutase and allopurinol, a xanthine oxidase inhibitor, were found to prevent this unfavourable chain of

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08808.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The long‐term outcome in rat kidneys subjected to 45 min of warm ischaemia with no treatment and after administration of 20 mg superoxide dismutase (SOD) and of SOD combined with 2 ml of a 12% sucrose solution was studied by the micropuncture technique. It was found that, although in the acute phase SOD prevented trapping of erythrocytes in the medullary vasculature and that SOD + sucrose also prevented the formation of tubular obstruction, the long‐term results as studied 1 week and 1 month after the primary ischaemic insult were virtually identical. This was due to the formation of new obstructions, during the first week, mainly in the thick ascending limb of Henle's loop. After 1 month the proximal tubular free‐flow pressure and the single‐nephron filtration rate had returned to normal. However, since the total glomerular filtration was only one‐third of that under normal conditions, it would seem that two‐thirds of the nephrons had undergone complete degeneration. This degeneration was probably the result of persistent tubular obstruction. The tubular degeneration was also accompanied by a reduction in urine osmolality and potassiu

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08809.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Histopathological changes in kidneys subjected to 45 min of isothermic unilateral ischaemia in the acute phase and 1 week and 1 month after primary damage were studied at the electron microscopic level. During the first week after recirculation long homogeneous cylinders, probably consisting of Tamm‐Horsfall protein, developed in the medullary parts of the nephron, and after 1 month of recirculation there were two types of nephrons: (1) nephrons with a normal histological appearance and (2) degenerated nephrons. The latter group gave rise to crypts in the outer cortical area. It is hypothesized that the generation of the long Tamm‐Horsfall cylinders in the thick ascending limb of the loop of Henle plays an important role in the long‐term outcome of the kidney after the primary damage. The persistent blockade caused by these cylinders will lead to precipitation of the ultrafiltrate, resulting in long cell‐protein cylinders in the proximal parts of the nephron. This precipitation will proceed in the retrograde direction, reaching the mother glomeruli, eventually leading to total degeneration of the

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08810.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The airway vascular and bronchial responses were studied in pigs sensitized withAscaris suum.Ascaris, histamine (H) and capsaicin aerosol all induced a clear‐cut increase in blood flow in the nasal, laryngeal and bronchial circulation with a decrease in vascular resistance of 20–40%. When delivered to the lung both ascaris and histamine, but not capsaicin, caused pulmonary airflow obstruction with increase in resistance and a fall in dynamic compliance of 40–70%. After pretreatment of pigs with a combination of the H1‐ and H2‐receptor antagonists terfenadine and cimetidine, the vascular and bronchial responses were strongly reduced to both histamine (by>77%) and ascaris (by>58%), but not to capsaicin aerosol. The bronchoconstriction to histamine was found to be mediated by H1‐receptors only, while both H1‐ and H2‐antagonists were necessary to block the vasodilatory response, with H2‐receptors being more important in the bronchial circulation and H1‐receptors being more important in the laryngeal and nasal circulation. Furthermore, when pigs were pretreated with capsaicin systemically 2 days before the experiment, the vasodilatation was decreased upon capsaicin (by 80%), ascaris (by>40%) and histamine (by>50%) aerosol challenge. When histamine was administered intravenously the desensitizing effect of capsaicin pretreatment was much less pronounced. The effect of capsaicin desensi‐tization on the pulmonary obstruction upon ascaris and histamine challenge was limited to a 60% reduction of the fall in dynamic compliance and a delayed peak in resistance upon ascaris challenge.We conclude that histamine is one of the main vasodilatory mediators released upon allergen challenge at three different levels of the pig airways. A considerable part of the histamine effect is indirect and probably due to activation of capsaicin‐s

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08811.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Removal of the renal pelvis in order to expose the renal papilla has been shown to cause impairment of the renal concentrating ability by an unknown mechanism. To study this phenomenon, urine osmolality (Uosm), single‐nephron glomerular filtration rate (SNGFR) in outer and inner cortical nephrons and the inner and outer medullary plasma flow were determined. Measurements were performed on groups of rats before (control) and 15, 45 and 90 min after exposure of the left renal papilla. Rats with an intact ureter were studied in parallel to see whether the variables varied within the 90‐min period of the study. In all groups of animals with an exposed papilla,Uosmwas lower than in non‐exposed animals. Outer cortical SNGFR in rats with exposed papillae, regardless of time, was not different from that in control rats. Inner cortical SNGFR after 45 and 90 min of exposure did not differ from that in controls, but after 15 min of exposure it was lower than in control animals. Outer and inner medullary plasma flow did not differ between rats with exposed papillae and controls, irrespective of exposure time.In conclusion, papillary exposure results in a permanent decrease in urine osmolality. This impairment of the concentrating ability cannot be attributed to prolonged changes in renal haemodyn

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08812.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Previous evidence for cerebral sodium/angiotensin interaction concerning centrally mediated effects of angiotensin II (All) provided the incitement to compare in goats effects of i. v. All during sodium repletion (SR) with those obtained during mild sodium depeletion (SD). The experiments were performed in the euhydrated as well as hyperhydrated animals, and All was infused for 10 min at 40 pmol kg‐1min‐1. It was confirmed that SD is associated with elevated plasma aldosterone concentration (PA) and (as regards aldosterone secretion) a sensitization of the adrenal cortex. In contrast to PA, the plasma Cortisol (PC) response to i. v. All was significantly reduced during SD, apparently due to diminished cerebral sensitivity to circulating AIL A similar SD‐associated attenuation was observed during euhydration as regards release of arginine vasopressin (AVP) in response to i. v. All, and during hyperhydration as regards the antidiuretic effect of the octapeptide. It was confirmed that the pressor effect of i. v. All becomes markedly reduced during SD. However, in spite of this, the associated bradycardia remained the same during SR and SD, suggesting that SD also attenuated the centrally mediated chronotropic effect o

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08813.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

A pH‐stat technique was used to investigate the effects of cholera toxin (CT) on alkaline secretion from denervated intestines (jejunum, ileum, colon) in anaesthetized rats. Transepithelial potential difference (PD) was also followed in some experiments. CT, given intraluminally, caused a marked increase in jejunal alkaline secretion, whereas only a small effect was observed in the ileum and no apparent effect was noted in the proximal colon. The pronounced increase in jejunal alkaline secretion was found to be inhibited by 10–25% by hexamethonium (10 mg kg‐1body wt i. v.) and similarly by serosal application of lidocaine, whereas atropine (0.25 mg kg‐1body wt i. v.) had no effect. Thus the cholera toxin‐induced alkaline secretion in the jejunum is attributed mainly to a non‐nervous mechanism. The small effect of CT on ileal alkaline secretion observed in this study contrasts with the high ileal bicarbonate concentration reported in cholera by authors who estimated the concentration from the total carbon dioxide/bicarbonate contents. This discrepancy may be explained by a CT‐evoked increased transport of the coupled Na+/H+and Cl/HCO3‐exchangers, which cannot be measured with the pH‐stat technique u

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08814.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Water intake and changes in plasma and cerebrospinal fluid (CSF) composition were measured in response to intracerebroventricular (i. e.v.) and intracarotid infusions of hypertonic NaCI solutions and after 48 h of water deprivation in sheep. Significant interindividual differences in dipsogenic sensitivity to i. e.v. NaCI were found, whereas no such differences were observed in response to intracarotid infusion of hypertonic NaCI. In the more sensitive animals, the increase in CSF [Na] at initiation of drinking during i. e.v. infusion did not differ significantly from the increase in plasma [Na]seen at the thirst threshold during intracarotid infusion of 1 M NaCI. The thirst‐eliciting infusions of hypertonic NaCI into the carotid arteries were associated with a small, significant, increase in CSF [Na], which however did not differ from that caused by an i. e. v. non‐dipsogenic ‘control’ infusion of a slightly hypertonic (0.154M) NaCI solution. Water deprivation for 48 h induced increases in CSF and plasma [Na] similar to those observed at the onset of drinking in response to i. e.v. and intracarotid infusions of hypertonic NaCI. However, the dehydrated animals drank about four times the amount of water consumed in response to the separate treatments with hypertonic NaCI.It is concluded that significant interindividual differences in dipsogenic sensitivity to osmotic stimuli are present in sheep, and that these differences may not necessarily be simultaneously expressed on both sides of the blood‐brain barrier.The thirst‐eliciting effect of intravascular infusion of hypertonic NaCI may be induced without concomitant increase in CSF [Na] and/or osmolality.A simultaneous increase in CSF and plasma [Na] and/or osmolality is suggested to contribute to the conspicuous water consumption seen in response to dehydration compared to that caused by acute administration of hype

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08815.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY