Urographic Excretion Study.

Abstract

Previous papers have suggested that a maximum urinary radioopacity is achieved in mail when an adequate dose of contrast agent is given after suitable dehydration (Benness, 19651, and that this maximum radioopacity may be rclatrd to renal function (Henness et al., 1965). This concept has been confirmed in the laboratory using sheep (Renness, 3967), and the work has heen continued to define the influence of different urographic agents on urinary radioopacity. MATERIALS .mi) METHODSX method of controlling the fluid balance of a young female sheep in a metabolic cage and of measuring the changes in plasma osmolality and contrast levels, urinary flow rate, osmoldity, contrast and electrolyte levels have been described (Benness, 1967). Blood samples were obtained through a percutaneous catheter inserted into the jugular vein, and urine samples were obtained by dependent drainage from a self-retaining bladder catheter. The animal was conscious and supported in a sling. The measurements on the blood and urine have been described.On separate occasions the animals were given equivalent doses of sodium or methylglucamine diatrizoate (NaD and MGD), or sodium or rnethylglucamine iothalamate (NaI and MGI). These doses had equivalent radioopacity (iodine content) rather than equivalent weight. Later they were given equivalent doses of sodium chloride 5% or methylglucamine hydrochloride 14.5% (NaC1 and MGHCl) on separate occasions.The plasma and urinary diatrizoate and iothalamate levels were measured by a spectrophotometric method (British Pharmacopoeia, 1963), calibrated with known standards, and expressed as NaD for convenient comparison. Urinary methylglucamine excretion was measured by a method of periodate oxidation (Ryan, personal communication), calibrated with known standards, and expressed as MGD for comparison. The details of the spectrophotometric estimation for the four contrast agents and the periodate estimation of methylglucamine will be reported in another paper. * Presented to the Annual Meeting, College of Radiologists of Australia and New Zealand, October, 1967. __ RESULTSThirty-three experiments were performed on four sheep, comparing the urinary response to the four contrast agents and the NaCl and MGHCl. On all occasions the sheep were given a normal dry food ration up to the time of the experiment, but they had no water for the previous three days. The large volume of the sheep's stomach was stabilized in this way and the dehydration, as measured by the urinary flow rate and osmolality, wa5 satisfactory and reproducible.The response in a dehydrated sheep to equivalent doses of contrast agents is illustrated in Figure 1. Doses equivalent to 1OOOmg. per kg. of NaD were used, containing approximately 600 mg. per kg. of iodine. This dosage scale was equivalent to a human infusion dose. Following control collections of blood and urine, the contrast agent was injected intravenously over one minute, and urine samples were collected for periods of 5, 5, 5, 10, 10, 10 and 15 minutes. Venous blood was sampled...

Comparison of the Excretion of Sodium and Meglumine Diatrizoate at Urography with Simulated Compression: An Experimental Study in the Rabbit

“…At higher doses, especially at 640 mg I/kg body weight during ureteral occlusion, and more markedly in estimated density than in urinary iodine concentration, the sodium salt is, however, the superior. Benness (1968Benness ( & 1970 obtained a higher urinary iodine concentration when applying sodium salt than meglumine salt. In his experiments, however, Benness used considerably longer sampling periods, and did not apply ureteral occlusion.…”

“…1970;Benness 1970;Benness & Glazer 1973;Dacie & Fry 1971). This is thought to be due to the greater urinary solute load produced by the meglumine agent because of the added excretion of the non-opaque meglumine ion (Benness 1968;Evil1 & Benness 1975b). According to our experiments, the sodium salt of diatrizoate in adose up to 320 mg I/kg body weight is not superior to the meglumine salt.…”

“…It has usually been agreed that the meglumine salt of a contrast medium, through the osmotic action of the non-opaque meglumine ion, will result in a higher diuresis than the sodium salt (Cattell ei a/. 1970;Benness 1968Benness & 1970AlmCn et al 1973;Evill & Benness 1975a;Knoefel et al 1974). In o u r experiments we found n o difference between the two salts up t o a dose of 320 mg I/kg body weight and a t higher doses a more pronounced diuresis when using the sodium salt than the meglumine salt, mostly during the first urine sampling period.…”

Urography Preparation and Anti‐diuretic Hormone

“…T h e dosage of contrast agent is the most important single factor in determining the final urinary iodine concentration. Concerning contrast agents, experiments (Benness, 1968Cattell et al, 1970;Pearson 198 et al, 1971;Dacie and Fry, 1971) showed a higher urinary iodine concentration with sodium salts rather than methylglucamine salts. Benness (1968) suggested that the reason for this is the different osmotic diuretic effects of sodium and methylglucamine ions.…”

Local Toxicity of Metrizamide on Intravascular Injection

“…They offered the hypothesis that the preventive effect might be osmotic diuresis. The contrast media used are hyperosmotic and increase the diuresis considerably without any premedication (BENNESS 1968). Metrizamide has, as a non-ionic compound, nominally half the osmotic pressure of the monomer ionic media.…”