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Biomedical subjects

V Arroyo

Publications and source records attributed to V Arroyo.

At least 163 records · Page 9Linked to original sources
PubMed1989

Effects of atrial natriuretic peptide on urinary kallikrein excretion and renal function in rats.

We investigated whether the renal kallikrein-kinin system is involved in the renal effects of atrial natriuretic peptide (ANP) by measuring the glomerular filtration rate (GFR), urine volume (UV) and urinary excretion of sodium (UNaV) and kallikrein (UkkV) in 4 groups of 10 anesthetized rats before and during (two 10 min periods) the i.v. infusion of Ringer solution (control group) or different doses of ANP (0.25, 0.5 and 1 microgram, respectively). The administration of ANP was associated with a marked and significant increase in UV, UNaV, UkkV and GFR. The diuretic and natriuretic responses to ANP were dose-related, while the changes in GFR and UkkV were short-lived and not related to the dose of ANP. There was no relationship between UV or UNaV and UkkV after ANP administration. In contrast, UkkV correlated closely with GFR (r = 0.675, P less than 0.001). These data do not support the hypothesis that the kallikrein-kinin system contributes to the diuretic and natriuretic effects of ANP, but it might be involved in the renal hemodynamic action of this peptide.

Animals↗
PubMed1989

Endotoxin-induced ascites formation in the rat: partial mediation by platelet-activating factor.

Systemic endotoxemia has been observed in patients with acute and chronic liver failure, and bacterial endotoxin is known to increase vascular permeability. We investigated in the normal rat the effects of intraportal endotoxin administration and the possible mediation of these effects by platelet-activating factor. Injection of endotoxin lipopolysaccharide (10 and 25 mg per kg) in the rat resulted in rapid ascites formation, as well as systemic hypotension, hemoconcentration and acute erosions of the gastrointestinal mucosa. These effects were significantly attenuated by pretreatment with L652,731 and CF-3988, specific platelet-activating factor antagonists. Administration of 25 mg per kg endotoxin also resulted in significant elevations of platelet-activating factor biosynthesis in vitro by samples of duodenum, liver and lung. The effects of endotoxin were mimicked by intraportal infusion of platelet-activating factor (50 ng per kg per min), which induced ascites and gastrointestinal lesions. Platelet-activating factor reduced circulating plasma volume and increased peritoneal permeability to albumin as assessed by the ascites to plasma ratio of labeled albumin. These results, therefore, support a role for platelet-activating factor in mediating endotoxin-induced ascites and gastrointestinal erosions.

Animals↗
PubMed1989

Blockade of the hydroosmotic effect of vasopressin normalizes water excretion in cirrhotic rats.

Water retention in cirrhosis has classically been considered to be due to a low distal fluid delivery secondary to increased proximal sodium reabsorption. However, recent studies showing high plasma vasopressin levels in patients and rats with cirrhosis, ascites, and dilutional hyponatremia suggest that a nonosmotic vasopressin hypersecretion could be an alternative mechanism. To investigate the role of vasopressin in water retention in cirrhosis, the renal ability to excrete a water load (50 ml/kg body wt), as estimated by the minimum urinary osmolality and the percentage of the water load excreted during 3 h, was assessed in 10 control rats and in 20 cirrhotic rats with ascites and impaired water excretion and high urinary excretion of vasopressin. Twenty-four hours later, the same procedure was repeated in cirrhotic rats 20 min after the subcutaneous injection (30 micrograms/kg body wt) of d(CH2)5Tyr(Et) VAVP, an antagonist of the hydroosmotic effects of vasopressin (10 rats), or the vehicle (10 rats). Treatment with the vasopressin antagonist normalized water excretion in 9 of the 10 rats. No significant changes in renal water metabolism were observed in the group of rats given the vehicle. These results indicate that vasopressin hypersecretion is the predominant mechanism of the impairment in water excretion in rats with experimental cirrhosis and ascites.

Animals↗
PubMed1989

Role of altered systemic hemodynamics in the blunted renal response to atrial natriuretic peptide in rats with cirrhosis and ascites.

The natriuretic effect of pharmacological doses of atrial natriuretic peptide (ANP) is markedly reduced in cirrhosis with ascites. The current study, which includes two protocols, was carried out to investigate whether this phenomenon is related to the altered systemic hemodynamics present in cirrhosis. In protocol A, the administration of ANP (2.5 micrograms.kg-1 as a bolus followed by a constant infusion of 0.1 microgram.kg-1.min-1) to 10 rats with carbon tetrachloride-induced cirrhosis and ascites produced a significantly lower increase in diuresis (13.4 +/- 1.3 microliters/min) and natriuresis (2.3 +/- 0.3 mu Equiv/min) than in 10 control rats (56.3 +/- 1.4 microliters/min and 8.7 +/- 0.5 mu Equiv/min, respectively), indicating a renal resistance to the effect of ANP in this experimental model of cirrhosis. The reduction of arterial pressure induced by ANP was similar in both groups. However, since baseline mean arterial pressure was significantly lower in cirrhotic rats, the degree of hypotension during ANP infusion was also greater in this group of animals (82 +/- 3 vs. 109 +/- 2 mmHg). The aim of protocol B was to assess whether normalization of arterial pressure in cirrhotic rats increases the renal response to ANP. This protocol includes two groups of 10 rats with cirrhosis and ascites infused with a glucose solution containing norepinephrine (CT-NE rats) or angiotensin II (CT-AII rats) at doses to normalize arterial pressure and an additional control group of 10 cirrhotic rats with ascites receiving only glucose solution (CT rats). Angiotensin II, but not norepinephrine or glucose solution administration, was associated with a significant increase in urine volume and sodium excretion. During ANP infusion, CT rats showed a blunted diuretic and natriuretic response. In contrast, the ANP-induced increase in urine volume and sodium excretion observed in CT-NE (53.6 +/- 10.4 microliters/min and 9.3 +/- 2.2 mu Equiv/min) and CT-AII rats (98.3 +/- 11.6 microliters/min and 15.5 +/- 2.9 mu Equiv/m), was similar or even greater than that showed by the healthy rats of protocol A. The degree of hypotension during ANP administration was also similar (CT-NE, 104 +/- 2; CT-AII, 108 +/- 5 mmHg). These results suggest that the blunted response to pharmacological doses of ANP in cirrhosis with ascites is related to altered systemic hemodynamics of cirrhosis, which further deteriorates during the infusion of the peptide.

Angiotensin II↗
PubMed1989

Treatment of ascites and renal failure in cirrhosis.

Ascites is a frequent complication in patients with liver cirrhosis. The accumulation of fluid in the abdominal cavity is associated with disturbances of systemic and splanchnic haemodynamics and of kidney function, which contribute to the poor prognosis of these patients. Classically, the treatment of ascites in patients with cirrhosis has been based on the combination of a sodium-restricted diet and the administration of diuretics. However, this treatment is not entirely satisfactory, since it is associated with a relatively high incidence of side-effects, and about 20% of patients hospitalized for the treatment of an episode of ascites do not respond to such therapy. In the last two decades, alternative therapies to diuretics have been introduced. PVS is an effective method of treating ascites. The high incidence of complications observed in early studies may be reduced by adequate perioperative management and careful selection of patients. The role of the PVS in the treatment of cirrhotics with ascites, however, still remains to be established. Recently, paracentesis has emerged as an alternative method of treating ascites in patients with cirrhosis. Several studies have shown that therapeutic paracentesis plus i.v. albumin infusion is more effective than conventional diuretic therapy and is associated with a lower incidence of complications. It has also been demonstrated that therapeutic paracentesis without the i.v. administration of albumin is associated with a marked increase in plasma renin activity, suggesting an impairment of effective blood volume, and with the development of hyponatraemia and/or renal failure in 20% of cases. Therefore, the i.v. administration of albumin is an essential measure in preventing the impairment of systemic haemodynamics and renal function that frequently follows the mobilization of ascites by paracentesis.

Ascites↗
PubMed1988

Prognostic value of arterial pressure, endogenous vasoactive systems, and renal function in cirrhotic patients admitted to the hospital for the treatment of ascites.

To identify prognostic factors in cirrhotic patients admitted to the hospital for the treatment of an episode of ascites, a survival analysis was performed in a series of 139 patients hospitalized in our Unit between 1980 and 1985. Mean follow-up was 12.8 +/- 14.2 mo (mean +/- SD). A total of 38 variables based on history, physical examination, hepatic biochemical tests, renal function tests, and endogenous vasoactive systems were analyzed for prognostic value. Eighteen of these variables had prognostic value in the univariate analysis. A multivariate analysis (Cox's regression method) disclosed that 7 of these 18 variables had independent prognostic value. Of these independent predictors of survival, mean arterial pressure and plasma norepinephrine concentration were the variables that best predicted prognosis. Two other variables that independently correlated with survival were urinary sodium excretion and glomerular filtration rate. The remaining three independent predictors of survival were nutritional status, hepatomegaly, and serum albumin concentration. Therefore, these findings indicate that, in patients with cirrhosis and ascites, parameters estimating systemic hemodynamics and renal function are better predictors of survival than those routinely used to estimate hepatic function.

Adult↗
PubMed1988

Randomized comparative study of therapeutic paracentesis with and without intravenous albumin in cirrhosis.

It has recently been shown that repeated large-volume paracentesis associated with intravenous albumin infusion is a rapid, effective, and safe therapy of ascites in cirrhosis. To investigate whether intravenous albumin infusion is necessary in the treatment of cirrhotics with large-volume paracentesis, 105 patients with tense ascites were randomly allocated into two groups. Fifty-two patients (group 1) were treated with paracentesis (4-6 L/day until disappearance of ascites) plus intravenous albumin infusion (40 g after each tap), and 53 (group 2) with paracentesis without albumin infusion. After disappearance of ascites, patients were discharged from the hospital with diuretics. Patients developing tense ascites during follow-up were treated according to their initial schedule. Paracentesis was effective in eliminating the ascites in 50 patients from group 1 and in 48 from group 2, with the duration of the hospital stay being approximately 11 days in both groups. Paracentesis plus intravenous albumin did not induce significant changes in standard renal function tests, plasma renin activity, and plasma aldosterone. In contrast, paracentesis without albumin was associated with a significant increase in blood urea nitrogen, a marked elevation in plasma renin activity and plasma aldosterone concentration, and a significant reduction in serum sodium concentration. One patient from group 1 and 11 from group 2 developed renal impairment or severe hyponatremia after treatment, or both (chi 2 = 9.19; p less than 0.01). The development of these complications could not be predicted by clinical and laboratory data before treatment. Although the probability of survival after entry into the study was similar in patients from both groups, a multivariate analysis identified the development of hyponatremia or renal impairment, or both, following the first paracentesis treatment and the occurrence of other complications during the first hospitalization (encephalopathy, gastrointestinal bleeding, and severe infection) as being the only independent predictors of mortality. These results indicate that intravenous albumin infusion is important in avoiding renal and electrolyte complications and activation of endogenous vasoactive systems in cirrhotics with ascites who are treated with repeated large-volume paracentesis. The development of such complications may impair survival in these patients.

Albumins↗
PubMed1988

Prostaglandin precursor fatty acids in cirrhosis with ascites: effect of linoleic acid infusion in functional renal failure.

1. Functional renal failure (FRF) in cirrhosis with ascites could be related to an inappropriately low renal prostaglandin (PG) production. To investigate whether the impaired renal PG synthesis in these patients is related to a PG precursor fatty acid deficiency, serum levels of linoleic and arachidonic acids and the urinary excretion of PGE2, 6-keto-PGF1 alpha and thromboxane B2 (TxB2) were measured in 10 normal subjects, 17 non-azotaemic cirrhotic patients with ascites and 10 cirrhotic patients with ascites and FRF. 2. Serum linoleic acid levels were similar in the three groups studied. Both groups of cirrhotic patients showed lower arachidonic acid levels than normal subjects; however, non-azotaemic cirrhotic patients and patients with FRF did not differ in relation to serum arachidonic acid. 3. Non-azotaemic cirrhotic patients had higher urinary PGE2, 6-keto-PGF1 alpha and TxB2 excretion than normal subjects and cirrhotic patients with FRF. Patients with FRF showed similar urinary PGE2 and TxB2 and lower urinary 6-keto-PGF1 alpha than normal subjects. In all cirrhotic patients no significant correlation was found between serum linoleic and arachidonic acid levels and urinary PGs. 4. In seven patients with FRF an acute intravenous infusion of linoleic acid induced a marked increase in serum levels of this fatty acid. However, no increase in serum arachidonic acid levels and urinary PG excretion and no improvement in renal function was observed. 5. This study suggests that an arachidonic acid deficiency is present in cirrhotic patients with ascites but that this abnormality is not a major determinant of renal function and PG production in these patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Longitudinal study of renal prostaglandin excretion in cirrhotic rats: relationship with the renin-aldosterone system.

1. A cross-sectional study (protocol A) was performed in 19 rats with cirrhosis, induced by carbon tetrachloride (CCl4), and ascites and in 10 control animals to assess renal prostaglandin (PG) excretion in experimental cirrhosis. In an additional group of animals, including nine rats chronically exposed to CCl4 (CCl4 rats) and six control rats, a longitudinal study (protocol B) was performed to investigate the temporal relationship between changes in renal PG excretion, the renin--aldosterone system and renal function. 2. Urinary PG excretion was assessed by specific radioimmunoassay of PGE2, PGF2 alpha, 6-keto-PGF1 alpha and thromboxane (TX) B2 after extraction with octadecyl silica cartridges and h.p.l.c. purification. Recoveries for each prostanoid (61 +/- 8% for PGE2, 64 +/- 12% for PGF2 alpha, 65 +/- 11% for 6-keto-PGF1 alpha and 66 +/- 17% for TXB2) were determined in every sample by adding tritiated standards, and the final values were corrected according to the individual recoveries. 3. Cirrhotic rats with ascites in protocol A showed a significantly higher plasma renin and aldosterone concentrations and urinary excretion of 6-keto-PGF1 alpha and TXB2 than did control animals. Urinary excretion of PGE2 and PGF2 alpha, however, was significantly reduced in cirrhotic animals as compared with controls. 4. In CCl4 rats included in protocol B, there was a close chronological relationship between the activation of the renin-aldosterone system, as estimated by urinary aldosterone excretion, the onset of sodium retention and the increase in urinary excretion of 6-keto-PGF1 alpha and TXB2. The urinary excretion of PGE2 and PGF2 alpha in CCl4 rats was reduced throughout the study.(ABSTRACT TRUNCATED AT 250 WORDS)

6-Ketoprostaglandin F1 alpha↗
PubMed1988

Effect of atrial natriuretic peptide on arterial pressure and renal function in cirrhotic rats with ascites.

Glomerular filtration rate, urine volume, sodium excretion and mean arterial pressure were measured in 10 rats with Cl4C induced cirrhosis presenting sodium retention and ascites, and in 10 control rats before and during the iv administration of the 28 aminoacid rat alpha-Atrial Natriuretic Peptide (alpha-ANP) (a bolus of 1 microgram followed by a constant infusion of 33 ng/min). alpha-ANP induced a similar increase in glomerular filtration rate and filtered sodium load in both groups of rats. In contrast, the increase in urine volume and sodium excretion produced by alpha-ANP was significantly lower in cirrhotic rats (from 13.8 +/- 1.9 to 37.9 +/- 9.1 microliters/min., and from 0.5 +/- 0.1 to 3.3 +/- 1.0 microEq/min) than in control animals (from 14.6 +/- 1.3 to 102.5 +/- 17.7 microliters/min., p less than 0.005; and from 1.0 +/- 0.3 to 14.1 +/- 3.2 microEq/min., p less than 0.001). The results indicate that in rats with experimental cirrhosis and ascites there are blunted diuretic and natriuretic responses to alpha-ANP, probably as a consequence of the exaggerated tubular sodium reabsorption present in these animals.

Animals↗
PubMed1988

Effect of spironolactone on the renin-aldosterone system in rats.

PRA, PRC and the plasma concentration of aldosterone (Aldo) were measured in rats (Sp-rats) receiving a daily sc injection of Spironolactone, (Sp, 20 mg in olive oil) and in control rats (C-rats) receiving olive oil only. Animals were studied one day after starting treatment, 5 days on treatment or after 5 weeks on the study. PRA, PRC and Aldo were significantly increased in Sp-rats as compared to C-rats throughout all the study. In additional Sp-rats and C-rats, the urine volume, serum Na+ and K+ concentration, Na+ and K+ intake and the urinary excretion of Na+, K+ and aldosterone-18-glucuronide (UAldV) were serially measured during 5 weeks. The total radioactivity plasma clearance after an i.v. bolus injection of 3H-aldosterone was subsequently measured in (5 Sp-rats and 5 C-rats). No significant differences in serum Na+ and K+ concentration and in Na+ and K+ balance were observed between Sp-rats and C-rats. UAldV was significantly higher in Sp-rats than in C-rats during all the study. After 5 weeks on treatment the total radioactivity plasma clearance was significantly higher in Sp-rats than in C-rats. These results indicate that Sp, at high dosage, stimulates renin release and aldosterone secretion by a mechanism unrelated to alterations in Na+ and K+ balance.

Aldosterone↗
PubMed1987

Temporal relationship between the impairment of free water excretion and antidiuretic hormone hypersecretion in rats with experimental cirrhosis.

To investigate the temporal relationship between the impairment of water excretion, sodium retention, and antidiuretic hormone hypersecretion in cirrhosis, free water excretion (estimated by the minimum urinary osmolality) and urinary antidiuretic hormone excretion (which correlates with the plasma levels of this hormone) were measured weekly after an oral water load in 18 rats with carbon tetrachloride-induced cirrhosis and in 20 control animals. The onset of ascites (as an index of sodium retention) in cirrhotic rats was estimated by sequential paracentesis. Thirteen cirrhotic animals developed an impairment of water excretion 2-5 wk after the onset of ascites. The urinary excretion of antidiuretic hormone in these animals, which was normal before the impairment of water excretion, increased markedly within the week in which this abnormality was first detected and remained high thereafter. The remaining 5 cirrhotic rats did not experience an impairment of free water excretion in spite of developing ascites. The urinary excretion of antidiuretic hormone in these animals was similar to that of control rats during the entire study. In all urine samples obtained from cirrhotic rats, there was a highly significant direct linear correlation between the urinary excretion of antidiuretic hormone and the minimum urinary osmolality. Our results show the following: in rats with carbon tetrachloride-induced cirrhosis, sodium retention preceded the impairment of water excretion; and in these animals, the defect in water metabolism correlated chronologically and quantitatively with antidiuretic hormone hypersecretion. These findings are consistent with the concept that antidiuretic hormone is a major determinant of the impaired water metabolism in cirrhosis.

Animals↗
PubMed1987

Comparison of paracentesis and diuretics in the treatment of cirrhotics with tense ascites. Results of a randomized study.

To investigate whether paracentesis could be an alternative therapy for ascites, 117 cirrhotics with tense ascites were randomly allocated into two groups. Fifty-eight patients (group 1) were treated with paracentesis (4-6 L/day until disappearance of ascites) and intravenous albumin infusion (40 g after each tap). Fifty-nine patients (group 2) were treated with spironolactone (200-400 mg/day) plus furosemide (40-240 mg/day). Patients from group 2 not responding to diuretics were treated with a LeVeen shunt. After disappearance of ascites, patients from both groups were discharged from hospital and were instructed to take diuretics. Patients developing tense ascites during follow-up were readmitted to hospital and treated according to their initial schedule. Paracentesis was effective in eliminating the ascites in 56 patients from group 1 (96.5%) and did not induce significant changes in renal and hepatic function, plasma volume, cardiac index, peripheral resistance, plasma renin activity, plasma norepinephrine and antidiuretic hormone concentration, and urinary excretion of prostaglandin E2 and 6-keto-prostaglandin F1 alpha. Diuretics were effective in eliminating the ascites in 43 patients from group 2 (72.8%) (p less than 0.05). Ten patients in group 1 and 36 in group 2 developed complications during their first hospital stay (p less than 0.001). This difference was due to the significantly higher incidence of hepatic encephalopathy, renal impairment, and electrolyte disturbances occurring in patients treated with diuretics. The duration of hospital stay was 11.7 +/- 1.5 days for patients from group 1 and 31 +/- 2.8 days for patients from group 2 (p less than 0.001). The two groups did not differ significantly with respect to the probability of requiring readmission to hospital during follow-up, reasons for readmission, survival probability after entry into the study, and causes of death. These results indicate that paracentesis associated with intravenous albumin infusion is a fast, effective, and safe therapy for ascites in patients with cirrhosis.

Albumins↗