ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08890.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Ouabain‐sensitive (OS) O2consumption was determined in proximal tubular cells from weanling rats fed 21 % (normal‐protein, NP) or 50% (high‐protein, HP) protein diet for 4 days. Butyric acid 10‐3M was added as a substrate for mitochondrial respiration and the ionophore amphotericin B (10 μ ml‐1) was used to sodium‐load the cells. OS respiration was higher in HP than in NP cells in both DME and amino acid‐free electrolyte solution (ES). Amphotericin B significantly increased OS respiration in both NP and HP cells, implying that the Na‐K pump was activated by increased intracellular Na. In cells incubated in ES, addition of amino acids stimulated OS respiration significantly in HP cells (16.9 ± 1.4vs21.2 ± 1.1 nmol min‐1mg‐1protein) and in NP cells (13.9 ± 0.3vs14.9 ± 0.6 nmol min‐1mg‐1protein). Stimulation was significantly higher in HP cells (26 ± 4%) than in NP cells (7 ± 4%) (P<0.001). The amino acids did not stimulate ouabain‐insensitive respiration.The results indicate that an HP diet to weanling rats will increase proximal tubule cell Na, K‐ATPase‐dependent respiration by enhancing Na

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08891.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

In anaesthetized male Sprague Dawley rats the influence of the calcium entry blocker verapamil (2.4 mg h‐1kg‐1, i. v.) on renal superficial cortical (CO) and outer medullary (OM) blood flow was investigated with the aim of clucidating further the intrarenal heterogeneity in vasoreactivity. The blood flow of the two regions was monitored simultaneously with a laser‐Doppler flowmeter, using fibre probes with an outer diameter of 0.75 mm. One probe was directed towards the cortex and a second probe was inserted through the cortex and positioned in the outer medulla, measuring the flow within a hemisphere with a depth of 0.5‐1.0 mm. The OM probe position was verified by dissecting the kidneys after each experiment. Insertion of the OM probe did not affect whole‐kidney glomerular filtration rate, renal plasma flow or electrolyte excretion. Thirty minutes of verapamil infusion increased OM blood flow by 26%, but did not change CO blood flow (–1%). In spite of the increase in OM blood flow, the urine osmolality remained unaltered. Sodium excretion increased by 39%, while potassium excretion was unchanged. Mean arterial blood pressure decreased by 13%. In conclusion, this study has further supported the suggestion that the vasoreactivity is higher in the juxtamedullary than in the superficial cortical vasculature. The heterogeneity of the response is most probably due to the previously documented pressure drop along the interlobular arteries, which will create different haemodynamic conditions for the juxtamedullary and superficial afferent

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08892.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Metabolites of arachidonic acid are possible mediators of local renal vasoconstriction in burn shock. The prostanoid precursor arachidonic acid (AA) therefore was infused in the control period and at 1 and 2 h after scalding in anaesthetized rats. To avoid systemic effects, AA was infused at low doses directly into the renal artery through a thin cannula introduced through the aortic wall. After control observations 40% of the body surface was scalded in 80 °C water. Renal arterial blood flow (RBF), measured by an electromagnetic probe, fell to 70% and 58% of the control level at 1 h and 2 h after scalding respectively. Arterial blood pressure was almost maintained. Infusion of AA (5, 15 and 25 nmol) in the renal artery over 15 s caused no effects in the control period, whereas a dose‐dependent decrease in RBF was observed after scalding, and was most pronounced 2 h post‐burn. The highest dose of AA reduced RBF by 37% at I h and by 80% of preinfusion flow at 2 h after scalding. The AA‐induced decrease in RBF was abolished by blocking the thromboxane A2receptors with AH23848. In contrast, inhibition of prostacyclin synthesis or blocking of serotonin S2receptors did not significantly influence the response to AA during shock. Thus, infusion of AA into the renal artery caused a marked reduction of RBF after scalding, at doses that did not induce a change during the control period. The augmented effect of AA infusion maybe due to an increased capacity for synthesis of thromboxane A2(TxA2), and possibly PGH2and PGF2α, after s

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08893.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Exocrine and endocrine release of rat submandibular gland kallikrein has been shown to be low after parasympathetic and β‐adrenergic stimulation but greatly increased after α‐adrenergic stimulation. In the present study, release of glandular kallikrein was investigated under conditions known to give a reflex‐induced salivary gland response.Heat stress induced a rich flow of saliva originating in the submandibular glands. Salivary kallikrein secretory rate was higher than after parasympathetic stimulation but lower than after sympathetic stimulation (P<0.005). Only heat stress increased circulating glandular kallikrein (12.7 ± 0.8 ng ml‐1before heat exposure and 53.3 ± 14.1 ng ml‐140 min afterwards,P<0.005). There were no indications that the endocrine release of kallikrein was due to non‐specific leakage. Atropine abolished heatinduced salivation and endocrine kallikrein secretion, possibly through interference with central pathways (P<0.05). However, phentolamine did not, which may indicate an as yet unidentified mediator of endogenous kallikrein release. The salivary gland response to acid and ether was comparable to that observed after parasympathetic nerve stimulation and was abolished by atropine (P<0.005). Stimuli known to influence other salivary gland ductal cells, such as aggression and starvation followed by drinking, also did not increase the plasma concentration of glandular kallikrein. The fact that various conditions which induce salivation did not increase circulating glandular kallikrein, coupled with the fact that kallikrein concentration was the highest in animals that died from heat stress, may suggest that the increase in circulating glandular kallikrein seen after heat stress may be pathological and could contribute to the developmen

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08894.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Survival and renal function were studied after 60 min of renal ischaemia and contralateral nephrectomy in four groups of French loop rabbits. One group served as untreated control animals. The other groups were pretreated with superoxide dismutase (SOD) and catalase, lidoflazine or a buffered albumin solution containing mannitol, L‐methionine and MgCl2. Six out of nine rabbits died during the 14‐day follow‐up period in the untreated control group, while the corresponding figure in each of the three treatment groups was one out of nine. Five of the rabbits that died exhibited azotaemia or hyperpotassaemia that could explain the death, while four died of non‐renal related causes. In the surviving animals, no differences in serum creatinine, potassium and sodium concentration or urinary output of osmoles was observed between the four groups. The increase in serum creatinine of the French loop rabbits observed after 60 min of ischaemia was considerably less pronounced than the corresponding increase observed in New Zealand White rabbits, indicating that the kidneys of the former strain are more tolerant to ischaemia. A cardiomyodepressant factor could be demonstrated in the venous effluent from previously ischaemic kidneys. This release could not be prevented by pretreatment with SOD and c

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08895.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

To investigate the diurnal variation in the plasma atrial natriuretic peptide (ANP) concentrations and its relation to renin activity, aldosterone, urine volume and electrolytes, blood samples from six healthy male subjects were collected and blood pressure and heart rate recorded every 4 h during a 24‐h sleep–wake period. Systolic blood pressure and heart rate were at the lowest during sleep. Plasma ANP, extracted on Sep‐Pak cartridges and measured by radioimmunoassay, had the highest concentration at midnight and lowest at 04.00 h (27 ± 18vs16 ± 18 ng I‐1, mean ± SD,P<0.05 after normalization of the original values). Plasma renin activity and aldosterone were at the highest at 08.00 and 12.00 h, whereafter they both began to decrease (P<0.001, also normalized). Urinary volume, sodium, potassium and chloride showed highest values (P0.05). Plasma renin activity correlated with aldosterone and aldosterone with urinary K (r= 0.66 and 0.58 respectively,P<0.001).These results suggest that the low plasma ANP levels found in our subjects at 04.00 h may be associated to diminished atrial distension accompanied by the inactivity of the sleep period. In addition, ANP does not appear to affect the secretion of renin and aldosterone in a normal slee

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08896.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The aim of this study was to elucidate the importance of biliary output for the regulation of migrating motor complex and the release of plasma motilin. Gallbladder emptying was monitored by hepatobiliary scintigraphy, plasma motilin concentration by radioimmunoassay and gastrointestinal motility by a perfused catheter system. During a total recording time of 46 h and 20 min in 16 volunteers, we observed 29 episodes of gallbladder emptying, 27 plasma motilin peaks and 23 activity fronts (phase 3 activity) of the migrating motor complex (MMC). Twelve episodes of gallbladder emptying started in phase I and continued into phase 2 of the MMC. The remaining 17 episodes of gallbladder emptying started in phase 2, and three of these continued into phase 3 of the MMC. Biliary output was associated with a significant rise in plasma motilin concentration, whereas plasma motilin significantly decreased after the activity fronts. These observations may explain the well‐known fluctuations of plasma motilin concentration in the fasted state. Motilin is released into the circulation as a result of biliary output, while the ensuing activity front of the MMC removes this stimulant from the proximal small bowel, resulting in a fall in plasma motilin. In conclusion, we have confirmed a temporal relationship between biliary output into the duodenum and the release of plasma motilin. The observed transition from phase 1 to phase 2 and from phase 2 to phase 3 of the MMC during gallbladder emptying episodes suggests that biliary output stimulates gastrointestinal motility in the fasted stat

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08897.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Peritonitis induced by serosal application of 0.1 M hydrochloric acid causes net fluid secretion via the enteric nervous system. The aim of the present study was to investigate present study was to investigate the roles of vasoactive intestinal peptide (VIP) and tachykinins in this reflex(es). The release of tachykinins (substance P [SP], neurokinin A [NKA], neuropeptide K [NPK]) and VIP into the mesenteric circulation, net fluid transport, intestinal blood flow and sometimes motility were recorded simultaneously in extrinsically denervated jejunal segments of the catin vivo. The release of both VIP and NKA was increased upon application of HCI to the cat jejunal serosa. Tetrodotoxin, hexamethonium and methionine enkephalin inhibited both the induced VIP release and the secretory response. The increased release of NKA was unaffected by hexamethonium.We propose that the intramural secretory reflex evoked by acid application of the serosa consists of an ‘afferent’ tachykinin neuron, a cholinergic interneuron and an ‘efferent’ VIPergic neuron innervating the secretory ente

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08898.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The interaction between changes of skin blood flow evoked by centrally mediated reflexes and local axon reflexes was studied in healthy subjects. Axon reflexes were evoked on the dorsum of the hand by transcutaneous electrical stimulation and reflex changes of blood flow by changes of ambient temperature, deep breath and emotional stress. Skin blood flow was measured by two laser‐Doppler flowmeters, the probes of which were situated 6–8 mm from the stimulating electrode (monitoring net flow responses) and several centimetres away (monitoring generalized reflex responses only). The axon reflex responses were markedly diminished by body cooling but did not change during body warming. In warm subjects, a deep breath and emotional stress caused transient reductions of the flow response evoked by the electrical stimulation. Regional anaesthesia of the nerve(s) innervating the stimulated skin area led to marked increases of axon reflex responses in cold subjects, but no changes occurred in warm subjects. The anaesthesia also eliminated the transient flow reductions evoked by deep breaths and emotional stress. Since the applied stimuli are known to change skin sympathetic activity, it is concluded that sympathetic (presumably vasoconstrictor) impulses destined for the skin may reduce axon reflex respon

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1990.tb08899.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY