Effects of furosemide diuresis on mercuric chloride-induced acute renal failure in the rat

In previous studies in rats given mercuric chloride (HgCl2), administration of furosemide has been found to either attenuate, exacerbate, or not affect the severity of the acute renal failure (ARF) otherwise expected to obtain. In the current study in rats given large doses of furosemide and in which urinary fluid losses were replaced by intravenous infusions of saline, administration of HgCl2 induced less severe ARF than that induced in rats not given furosemide and saline infusions. In rats not given furosemide, a diuresis induced by continuous reinfusion of urine also conferred protection against the nephrotoxic effect of HgCl2. These findings suggest that in rats given HgCl2: diuresis per se is the critical determinant of any salutary effect of furosemide and the protective effect of diuresis does not depend on renal elimination of mercury.

Expression of Sendai virus defective-interfering genomes with internal deletions

Sendai virus strain 7 has been shown to contain four defective interfering (DI) RNA species in which both genome termini and various adjacent fragments of the 3'-terminal NP gene and 5'-terminal L gene are represented, but most or all internal genes and gene boundaries are deleted. Previous sequence analyses of these mutant RNAs suggested that all four possessed the transcription initiation signal of the NP gene and the transcription termination signal of the L gene. The supposition that these signals should specify transcripts has now been supported by oligo(dT) selection of four DI 7 specific RNA species that had apparent molecular weights slightly lower than each DI genome. DI RNA 7a, which contains the entire NP gene, except for two U residues at the end of the poly(A) initiation signal, appeared to be transcribed solely as a readthrough product. Since DI RNA 7a contains the entire NP protein-coding sequence and DI RNAs 7c and 7d contain fragments of it, whereas DI RNA 7b is devoid of it, only transcripts of RNAs 7c and 7d were expected to specify fusion proteins containing NP gene-specific sequences. A strain 7-induced protein that reacted with monoclonal antibodies against the NP protein had the 33,000 Mr size appropriate for the translation product predicted by the sequence of RNA 7d. Other proteins of lower molecular weight were seen only in cells infected by strain 7, but they did not react with NP-specific antibody and their translation in vitro was not blocked by hybridization to an NP gene-specific oligonucleotide. Therefore, at least some of these proteins may be cellular products induced by DI virus infection. These DI transcripts and translation products may influence interference with replication of the parental helper virus.

Role of renal papillae in the regulation of sodium excretion during acute elevation of renal perfusion pressure in the rat

We studied the role of renal papillae in the mechanism of increased sodium excretion during acute increase in mean arterial pressure (MAP). Sodium excretion increased dramatically in normal rats after acute increase in MAP by epinephrine (E) infusion (0.4 micrograms/min/100g). Glomerular filtration rate (GFR), renal blood flow (RBF), and papillary plasma flow (PPF) remained unchanged after the E administration. To define the role of the medulla in the mechanism of pressure-induced natriuresis, experiments were performed in a group of rats 8 to 12 days after the development of papillary necrosis induced by bromoethylamine hydrobromide. Urinary sodium and fractional sodium excretions were 2.00 +/- 0.34 microEq/min and 2.37 +/- 0.53% (n = 7), respectively, in papillary necrosis rats infused with saline. Administration of E to papillary necrosis rats, however, failed to increase both urinary sodium (2.89 +/- 0.61 microEq/min) and fractional sodium (FENa, 2.82 +/- 0.63%, n = 6) excretions despite a marked increase in MAP (129 vs 150 mm Hg, p less than 0.01). The RBF increased slightly after E infusion (4.42 vs 3.24 ml/min/100 g, p less than 0.05), but the GFR was not different between the control (0.39 +/- 0.05 ml/min/100g, n = 7) and the E-treated rats (0.43 +/- 0.06, n = 6). Failure to increase sodium excretion during acute increase in MAP was not due to the decreased GFR, since control rats with bilateral partial nephrectomy were able to increase sodium excretion from 1.92 +/- 0.33 to 7.76 +/- 1.63 microEq/min (p less than 0.01) after E infusion. These findings, therefore, suggest that renal papillae play a major role in the mechanism of natriuresis during acute increase in MAP.

Renal phosphate excretion in spontaneously hypertensive and normotensive Wistar Kyoto rats

Renal tubular reabsorption of phosphate was studied in unanesthetized spontaneously hypertensive (SHR) and normotensive Wistar Kyoto rats (WKY). Three-hour-urinary phosphate excretions of 12-week-old-male SHR (53.0 +/- 13.1 micrograms/mg creatinine, N = 7) and 14-week-old female SHR (81.8 +/- 12.8, N = 8) were significantly lower than those of age sex-matched WKY (12 week, 435.8 +/- 73.2, N = 8, P less than 0.01; 14 week, 423.3 +/- 75.9, N = 8, P less than 0.01). Renal clearances were performed in 14-week-old female rats after an overnight fast. The serum phosphate concentration of SHR (4.61 +/- 0.25 mg/dl) was lower than that of WKY (5.44 +/- 0.14, P less than 0.02). Urinary phosphate excretion (U Pi V = 6.85 +/- 1.83 micrograms/min) and fractional phosphate excretion (FE Pi = 13.7 +/- 2.3%) of SHR were lower than those of WKY (U Pi V = 15.9 +/- 1.87 micrograms/min, P less than 0.01, FE Pi 22.8 +/- 2.6%, P less than 0.02). Acute hyperventilation could not account for the lower excretion of phosphate in SHR, since arterial pH and PCO2 were not different between WKY and SHR. The low renal phosphate clearance of SHR was noted at a very early age; the U Pi V of 5-week-old SHR was already lower than that of WKY. Maximum tubular phosphate reabsorption (TmPi) was studied in the 12-week-old SHR and WKY after acute thyroparathyroidectomy. TmPi of SHR (241 +/- 3.0 micrograms/ml GFR/100 g, N = 7) was greater than that of WKY (204 +/- 7.0, N = 8, P less than 0.01). However, the differences in 3-hr urinary phosphate excretion and clearances of phosphate were abolished between SHR and WKY after their blood pressures were lowered by chronic hydralazine treatment. The results indicate that hypertension is responsible for the lower renal phosphate clearances in SHR.

Bicarbonate hemodialysis: influence on plasma refilling and hemodynamic stability

The present study compares the effect of sodium bicarbonate (LoNaHCO3, Na = 134, HCO3 = 33 mEq/l) and sodium acetate (LoNaAc, Na = 134, acetate 33 mEq/1)dialysate on the extravascular fluid mobilization (VFM) and hemodynamic changes in 6 patients during 3 h of hemodialysis with equivalent fluid ultrafiltration of about 600 ml/h. The cumulative decrease in plasma volume after 1, 2 and 3 h of dialysis was significantly less during LoNaHCO3 dialysis than during LoNaAc dialysis, with plasma volume almost completely refilled by VFM during the first 2 h of LoNaHCO3 dialysis. High sodium acetate dialysate (HiNaAc, Na = 144, acetate = 33 mEq/1) with equivalent fluid ultrafiltration also resulted in less net decrease in plasma volume and greater VFM than LoNaAc, although the temporal pattern of refilling was somewhat different from that during LoNaHCO3: rapid and complete refilling during the early portion of LoNaHCO3, slower and more progressive refilling during HiNaAc, with similar cumulative refilling for LoNaHCO3 and HiNaAc by 3 h. Mean arterial pressure (MAP) tended to decrease during LoNaAc dialysis, whereas MAP remained stable during LoNaHCO3 and increased slightly during HiNaAc. This study, therefore, suggests that improved hemodynamic stability utilizing bicarbonate dialysate may be due, in part, to greater plasma refilling and better preservation of plasma volume.

Contribution of oligosaccharide sulfation to the charge heterogeneity of a viral glycoprotein

The single glycoprotein species of vesicular stomatitis virus exhibits heterogeneity in isoelectric focusing. Short term radioisotopic labeling of infected cells revealed that this heterogeneity is acquired after synthesis and glycosylation of the protein, during the period of oligosaccharide processing from the high mannose to the complex form. In this process, radioactive sulfate is incorporated randomly into different glycoprotein molecules, conferring unequal amounts of negative charge upon them. Since the virus glycoprotein is processed by cellular pathways, it is likely that differential sulfation is responsible for much of the charge heterogeneity displayed by cellular glycoproteins.

Site-specific phosphorylation regulates the transcriptive activity of vesicular stomatitis virus NS protein

In vitro transcription by vesicular stomatitis virus nucleocapsids is inhibited by enzymatic dephosphorylation of the NS protein. We provide evidence that specific, partial dephosphorylation of NS molecules is the only detectable change in nucleocapsids treated with bacterial alkaline phosphatase under conditions that prevent the action of adventitious protease. Dephosphorylation appeared to affect only the rate of transcription; there were no changes in sedimentation rates of transcripts. To identify the sites of phosphorylation required for NS activity in transcription, we examined phosphopeptides produced by chymotrypsin digestion of the two electrophoretic classes of NS molecules found in virions and infected cells. The electrophoretically slower class, NS1, abundant in the intracellular soluble pool, has a lower activity in transcription; it contained six chymotryptic phosphopeptides. Five of these peptides contained both phosphoserine and phosphothreonine, indicating that this peptide cluster represents at least 11 separate sites of phosphorylation. In the electrophoretically faster nucleocapsid-associated NS2 class of molecules, which support a higher rate of transcription, another group of eight phosphopeptides was superimposed on this pattern. Two of these peptides contained both phosphoserine and phosphothreonine, so this cluster of peptides represents at least 10 additional phosphorylation sites. These sites were especially sensitive to dephosphorylation by bacterial alkaline phosphatase. One or more of them appears to be responsible for the higher transcription rates medicated by NS2 molecules.

Segmental renal vascular resistance in the spontaneously hypertensive rat

Renal hemodynamics were studied during different stages of development of hypertension in unanesthetized spontaneously hypertensive rats (SHR). In SHR at 4 wks of age mean arterial pressure (MAP) was higher than in age-matched Wistar Kyoto rats (WKY); however, renal blood flow (RBF) and renal vascular resistance (RVR) were not different between these two groups. Mean values of RVR and MAP in 8- and 12-wk-old SHR were significantly greater than those of age-matched WKY. Both RBF of 8- and 12-wk-old SHR were significantly lower than the corresponding values of WKY. Afferent arteriolar diameter (AAD) was measured with a microsphere method. AAD was not different between 4-wk-old SHR and WKY; however, the AAD of 8-wk-old (16.3 +/- 0.23 micrometers, n = 5) and 12-wk-old (17.4 +/- 0.48, n = 5) SHR were significantly smaller than those of respective control WKY (17.3 +/- 0.34, n = 4, P less than 0.05; 19.3 +/- 0.12, n = 5, P less than 0.01). Calculated preglomerular (Rpre) and postglomerular resistances (Rpost) of 12-wk-old SHR were increased 96 and 129% when compared with respective segmental resistances of the control WKY. The decrease in AAD of 12-wk-old SHR was sufficient to account for a 33% increase in Rpre. After the rats were treated with hydralazine (0.5 mg/kg iv), MAP, RBF, and RVR of SHR were not different from the control WKY values. Rpre and Rpost of SHR were substantially decreased; however, vasodilation occurred at vessels proximal and distal to the afferent arteriole because AAD was not altered. Our results indicate that increased RVR in SHR involves increases in Rpre and Rpost.

The effect of renal perfusion pressure on renal vascular resistance in the spontaneously hypertensive rat

Renal hemodynamics and renal vascular resistance (RVR) were measured in the spontaneously hypertensive rat (SHR) and in the normotensive Wistar-Kyoto rat (WKY). In addition, the autoregulatory response and segmental RVR in the SHR were studied after aortic constriction. Mean arterial pressure (MAP) and RVR were higher in the SHR than in the WKY, but renal blood flow (RBF) and glomerular filtration rate were similar in both groups. Measurement of mean afferent arteriolar diameter (AAD) by a microsphere method showed a significantly smaller AAD in SHR (17.7 +/- 0.35 micrometers) than in the WKY (19.5 +/- 0.20 micrometers). This decrease in AAD could account for a 47% increase in preglomerular resistance. Aortic constriction in the SHR, sufficient to reduce renal perfusion pressure from 152 to 115 mmHg, did not alter the AAD. Since RBF and glomerular filtration were also well maintained following aortic constriction, these autoregulatory responses suggest that vessels proximal to the afferent arteriole rather than postglomerular vasculature are primarily involved in the changes on intrarenal vascular resistance in SHR.

NS phosphoprotein of vesicular stomatitis virus: subspecies separated by electrophoresis and isoelectric focusing

The NS protein of vesicular stomatitis virus is the only phosphorylated nucleocapsid protein. The amount of NS phosphorylation appears to regulate the activity of the protein in the transcription of the virus genome. Several methods have been used to separate NS subspecies containing different amounts of phosphate, but the relationships among the subspecies separated by different workers have been unclear. We report that the isoelectric points of NS molecules were abnormally acidic in some commercial ampholytes, but favorable ampholytes resolved multiple phosphorylated NS subspecies with isoelectric points ranging from pH 6.8 to 7.2. The most highly phosphorylated NS molecules had more acidic isoelectric points, and they exhibited greater electrophoretic mobilities in two previously employed electrophoretic systems.

Blood viscosity in experimental acute renal failure

We measured blood viscosity in rats 24 h after induction of acute renal failure by glycerol or HgCl2 injections. The blood viscosity values of rats with acute renal failure were significantly higher than those of controls at any shear rates. The mean values of plasma fibrinogen in animals with glycerol - (302.5 +/- 35.2 mg/100 ml) or HgCl2 - (342.1 +/- 15.9 mg/100 ml) induced acute renal failure were significantly elevated compared to control levels (169.6 +/- 16.7 mg/100 ml). We believe that the increased blood viscosity in acute renal failure was primarily due to high concentration of plasma fibrinogen. The elevated blood viscosity may affect capillary microvascular circulation of glomerular capillary beds.

Propranolol antagonizes phencyclidine-induced hyperactivity and stereotypy in rats

The single and combined effects of acute phencyclidine (PCP) and propranolol, each given intraperitoneally, were studied on rat behavior. PCP (5, 10, 25, 50, and 100 mg/kg) produced dose-related stereotypy and increases in (photocell) hyperactivity over 4 h observation. Propranolol (10 and 25 mg/kg) neither caused any stereotypy nor had any effect on activity relative to vehicle control. Additionally, propranolol (10 and 25 mg/kg), given 30 min after PCP (10, 25 and 50 mg/kg), reduced or completely blocked the stereotypy and hyperactivity caused by PCP. These data provide the first experimental verification of a clinical observation that propranolol may be an effective antagonist of the behavioral toxicity produced by PCP.

Preservation of plasma volume during hemodialysis depends on dialysate osmolality

Hypotension is a major complication of hemodialysis and has been variously attributed not only to plasma volume loss which results from ultrafiltrative fluid removal, but also to extracorporeal blood circulation, osmolar changes or hemodynamic abnormalities which complicate the procedure. The present investigation demonstrates that plasma volume loss during ultrafiltrative fluid removal is reconstituted by mobilization of extravascular fluid, and that the rate of mobilization depends on dialysate osmolality. 7 subjects underwent 2 sessions of hemodialysis differing only in the NaCl concentration and osmolality of the dialysate, each session with ultrafiltration of fluid averaging about 1,800 ml over 3 h. Higher dialysate osmolality resulted in (1) less net decrease in plasma volume, -160 ml vs. -590 ml; (2) more mobilization of extravascular fluid, 1,670 ml vs. 1,150 ml, and (3) better control of hypotension. These results suggest that higher dialysate osmolality improves hypotension and dysequilibrium during hemodialysis by altering the movement between body fluid compartments and preserving normal hemodynamic mechanisms.

Renal hemodynamics in experimental acute renal failure

Results from many laboratories, including our own, support the following view of the status of renal blood flow (RBF) in acute renal failure (ARF). During the initiation phase of virtually all forms of experimental ARF, RBF appears to be substantially decreased. The mechanisms for the decrease in RBF vary depending on the model employed. However, we have shown that changes in cardiac output are involved in both HgCl2 and glycerol models of ARF. The degree to which the decreased RBF contributes to the impaired glomerular filtration rate (GFR) characterizing the initial phase of ARF also depends on the particular model that is studied. In terms of the maintenance phase of ARF, out studies show that total RBF is essentially normal in both glycerol and HgCl2 models of ARF. A general consensus exists that RBF is not related to the decreased GFR in the maintenance phase of ARF, regardless of the model of ARF employed. Results from this laboratory suggest, however, that a hemodynamic mechanism may still contribute to the decreased filtration in ARF despite the dissociation between total RBF and GFR. This mechanism may involve an increase in preglomerular resistance, either alone or in association with a decrease in postglomerular resistance. An extensive amount of research has been performed on the renal circulation in ARF over the past two decades. It appears that this research has basically confirmed Ole Munck's impression of the role of renal blood flow in the pathophysiology of ARF.

Familial hyperuricemia and renal disease

Information on a familial syndrome of hyperuricemia and renal disease with or without gout was obtained on 33 of 41 blood relatives: Nine had renal disease; abnormalities of the urinary sediments were minimal; serum uric acid levels were elevated in seven and were not measured in two. Hyperuricemia was noted in three additional family members without evidence of renal disease. Goulty arthritis (three patients) did not precede renal disease. One individual had hyperuricosuria. The following erythrocyte purine enzyme levels were normal: adenine phosphoribosyltransferase, hypoxanthine-guanine phosphoribosyltransferase, phosphoribosylpyrophosphate, synthetase, adenosine deaminiase, and purine nucleoside phosphorylase. Renal biopsy specimens showed focal global and segmental sclerosis of glomeruli, occasional hypercellularity, foci of atrophic tubules, chronic interstitial inflammation, and folding and wrinkling of glomerular basement membrane without electron-dense deposits. There were no immunofluorescent abnormalities.

Effect of exogenous angiotensin II on renal hemodynamics in the awake rat. Measurement of afferent arteriolar diameter by the microsphere method

We measured cardiac output (CO), renal blood flow (RBF), renal plasma flow (RPF), and afferent arteriolar diameter by the microsphere method, and inulin clearance (GFR) simultaneously in awake rats given an infusion of exogenous angiotensin II (100 ng/min per kg). Angiotensin II did not affect the CO, whereas both RBF and RPF decreased significantly in rats infused with angiotensin II (RBF, 2.88 +/- 0.11, mean +/- SE; RPF, 1.78 +/- 0.09, n = 6) when compared to control animals given saline (RBF, 4.58 +/- 0.31; RPF, 2.80 +/- 0.24 ml/min per 100 g, n = 6, both P less than 0.005, respectively). Both mean arterial pressure (MAP) and renal vascular resistance (RVR) were significantly higher in rats infused with antiogensin II than in controls. The decrease in GFR did not parallel the reduction of RPF in rats infused with angiotensin II as reflected by their higher values of mean filtration fraction (41.1 +/- 1.6%, n = 6) than that of controls (33.7 +/- 2.4%, n = 6, P less than 0.05). Despite significant elevations of MAP and RVR in rats infused with angiotensin II, their mean afferent arteriolar diameter (19.6 +/- 0.24 micron) was not different from that of controls (20.1 +/- 0.39 micron). We conclude that angiotensin II preferentially acts at the site of postglomerular vasculature but not at the afferent arteriole.

Resolution of chylothorax after positive end-expiratory pressure ventilation

Ligation of the thoracic duct has previously been recommended for adults with traumatic chylothorax when average daily chyle loss exceeds 1,500 mL/day over five days since such cases are usually refractory to medical management. We describe a case of traumatic chylothorax where chyle output exceeded 2 L/day for a week despite cessation of oral intake and institution of intravenous hyperalimentation. The chylothorax rapidly resolved when mechanical ventilation with positive end-expiratory pressure was begun for treatment of an acute respiratory distress syndrome. The artificial ventilation may have promoted tamponade of the injured lymphatic duct thereby accounting for the abrupt decrease in chyle flow the occurred.