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S K Morcos

Publications and source records attributed to S K Morcos.

At least 73 records · Page 4Linked to original sources
PubMed1995

Relationship between the diuretic effect of radiocontrast media and their ability to increase renal vascular resistance.

The relationship between diuresis and natriuresis induced by radiocontrast media (RCM) and their renal haemodynamic effects were investigated. The effects of the iso-osmolar iotrolan and the hyperosmolar diatrizoate on the renal vascular resistance (RVR) were studied in the filtering and non-filtering variants of the isolated perfused rat kidney (IPRK) preparation. In the non-filtering model, no tubular regulatory process can be activated. The effect of diatrizoate on the RVR of the filtering IPRK in the presence of fursemide (0.3 mmol l-1) an inhibitor of the tubuloglomerular feedback (TGF) was also investigated. There was no significant difference (p > 0.05) in the response of the filtering (n = 6) and non-filtering (n = 6) IPRK to iotrolan. The induced reduction in the renal perfusate flow (RPF) by iotrolan was 20.5 +/- 3.05% and 22.9 +/- 3.03%, respectively. The reduction in the RPF which was observed with diatrizoate in the non-filtering IPRK (n = 5, 17.5 +/- 3.04%) was significantly less (p < 0.05) in comparison to that of the filtering IPRK (n = 6, 26.9 +/- 4.28%). In the frusemide experiments, a reduction in the RPF comparable to that of the non-filtering kidney was observed (n = 5, 13.7 +/- 4.34%). This study demonstrates that the renal vascular effect of diatrizoate is partially dependent on the TGF response. No tubular regulatory mechanism was accountable for the haemodynamic effect of iotrolan. The activation of the tubular response is osmolarity dependent.

Animals↗
PubMed1994

Reduced depression of renal function by iotrolan in the isolated rat kidney.

The direct effects of iotrolan, a non-ionic dimer, on renal function were compared to iopromide, a non-ionic monomer and diatrizoate, an ionic monomer using the isolated perfused rat kidney. Kidneys were perfused ex vivo at 100 mmHg in a recirculating perfusion system with an albumin-based perfusate containing angiotensin II. All contrast media were studied at starting concentration of 20 mg Iodine/ml of renal perfusate. Each contrast agent produced a biphasic effect on the glomerular filtration rate (GFR) characterised by a transient increase followed by a sustained fall. However, the sustained fall in GFR induced by iotrolan (-24.7 +/- 2.1%) was significantly smaller than that produced by diatrizoate (-40.6 +/- 3.5%, P < 0.05) but there was no significant difference in comparison to the fall induced by iopromide (-34.2 +/- 3.7%). Each contrast agent produced a sustained decrease in renal perfusate flow (RPF) with iotrolan exerting a significantly smaller response (-21.7 +/- 2.0%) than either diatrizoate (-29.4 +/- 2.6%, P < 0.05) or iopromide (-32.2 +/- 2.9%, P < 0.05). The results indicate that at an equivalent iodine concentration iotrolan produces a smaller reduction of renal function in comparison to either iopromide or diatrizoate.

Animals↗
PubMed1994

Role for endothelin in the renal responses to radiocontrast media in the rat.

1. The involvement of endothelin in the renal responses to radiocontrast media was examined in the rat in vitro and in vivo using BQ123, a selective endothelin (ETA) receptor antagonist, and phosphoramidon, an endothelin-converting enzyme inhibitor. 2. For experiments in vitro, an isolated perfused rat kidney was employed perfusing in closed circuit with an albumin-based Krebs-Henseleit solution. The effects of BQ123 and phosphoramidon on the renal responses to iotrolan (iso-osmolar radiocontrast media) and diatrizoate (high-osmolar radiocontrast media) were examined. In vivo, renal conductance was measured using a Doppler flow probe in the anaesthetized rat pretreated with indomethacin, and the effects of BQ123 and phosphoramidon on the renal response to intravenous diatrizoate were examined. 3. In vitro, iotrolan and diatrizoate both produced a biphasic effect on the glomerular filtration rate, characterized by a transient increase followed by a sustained fall. Pretreatment with BQ123 (10 mumol/l), but not phosphoramidon (1 mmol/l), prevented both the increase and the sustained fall in glomerular filtration rate induced by radiocontrast media. 4. In vitro, iotrolan and diatrizoate both produced a sustained fall in renal perfusate flow. An initial increase in renal perfusate flow was only observed with diatrizoate. Pretreatment with BQ123 (10 mumol/l), but not with phosphoramidon (1 mmol/l), markedly inhibited the sustained fall in renal perfusate flow produced by both iotrolan and diatrizoate. BQ123 (10 mumol/l), however, markedly potentiated the renal vasodilatation produced by diatrizoate.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

The functional effects of gadolinium-DTPA on the isolated perfused rat kidney.

Clinical experience suggests that Gd-DTPA has no deleterious effect on renal function. We have evaluated the effects of a large dose (0.6 ml/kg body weight) of this contrast agent on the function of the isolated perfused rat kidney. Gd-DTPA led to a mild, transient increase in glomerular filtration rate with no subsequent fall during the 30 minute observation period. However, Gd-DTPA induced an increase in renal vascular resistance (+ 10%, P < 0.05) as a mild decrease in renal perfusate flow was observed during the experimental phase when compared to that of control kidneys. No significant effect was demonstrated on the fractional excretion of albumin or the fractional reabsorption of sodium. These data support, in an ex vivo experimental model, the clinical experience of the safety of this paramagnetic contrast agent in relation to renal function.

Animals↗
PubMed1993

The histological response of the lungs of rats to potentially suitable water soluble bronchographic contrast agents iotrolan (a non-ionic dimer) and iopamidol (a non-ionic monomer).

The recent need for selective bronchography during bronchoscopy in certain patients, together with paediatric indications for tracheo-bronchography, raises the question as to which contrast medium is both safe and efficient. The purpose of the present experimental study was to define the tissue reaction caused by iotrolan and iopamidol in the bronchi and lungs of rats. 60 animals used in this study were divided into five groups receiving iotrolan 300, iopamidol 370, iopamidol 150, physiological saline and anaesthetic only, the last two acting as control groups. Statistically there was no significant difference in the histological reaction between iotrolan 300, iopamidol 370 and iopamidol 150 compared with the control groups, although iotrolan 300 appeared to result in the least tissue reaction. With its adequately high iodine concentration, low osmolality and relatively high viscosity, iotrolan 300 would appear to be a suitable contrast medium for bronchography.

Animals↗
PubMed1992

Effect of diatrizoate on the function of the isolated perfused rat kidney.

The mechanism of the nephrotoxicity of water-soluble contrast media (WSCM) remains ill defined. We have studied the effect of diatrizoate on the isolated perfused rat kidney (IPRK). Emphasis was on the effect of low- and high-dose diatrizoate on glomerular filtration rate (GFR), renal perfusate flow (RPF), fractional excretion of albumin (FE Alb) and fractional reabsorption of sodium (FR Na). The addition of diatrizoate to the IPRK led to a dose-dependent biphasic change in RPF and GFR characterized by an initial transient increase followed by a marked and sustained decrease. Diatrizoate induced a diuresis and a parallel increase in urinary sodium excretion (fall of FR Na). Fe Alb was also increased in kidneys exposed to diatrizoate. Electron microscopy of a control kidney showed preservation of cellular architecture, which contrasted with the observed cytoplasmic vacuolation of proximal tubular cells after perfusion with diatrizoate. This study confirms a direct effect of WSCM on the function of the IPRK. In this experimental model, diatrizoate reproduces the effects observed in vivo on GFR and renal perfusion.

Animals↗