Intraperitoneal toxicity of Hytrast: an experimental study.

The toxic effects of Hytrast were studied on the peritoneum of laboratory rats in order to define the lethal dose and possible causes of toxicity. The results show that Hytrast, due to its toxicity, should not be used in any clinical situation where gastrointestinal tract perforation or leakage is a possibility.

Effect of viable isolated hepatocytes or hepatocyte fractions on survival rate following galactosamine-induced acute liver failure.

Administration of galactosamine to rats results in an acute liver failure. The dose-effect relation appeared to be highly strain-dependent. Intraperitoneal injection of 1,000 mg/kg galactosamine resulted in a 90% lethal acute liver failure in Wag/Rij rats. Transplantation of viable isolated hepatocytes, administration of homogenate or cytosol of normal or regenerating liver tissue, or administration of cell-free liver cell culture supernatant did not improve the survival rate in this model of acute liver failure. These findings, which are in striking contrast with the data reported in the literature, are discussed in relation to the specific properties of this type of experimental model for acute hepatic failure.

Experimental evaluation of various available contrast agents for use in the upper gastrointestinal tract in case of suspected leakage. Effects on lungs.

The reactions of seven contrast agents--pure barium sulphate, Micropaque, Gastrografin, Dionosil, Hytrast, Amipaque and Hexabrix--on the bronchi and lungs of rats were studied. This work was undertaken to find a safe gastrointestinal contrast agent for use in post-operative patients where aspiration may be an accompanying risk. Amipaque and Hexabrix produced no significant histological reaction in the lungs and would, therefore, appear to be suitable for use in such cases.

Effect of propranolol on surgical bleeding and hemostasis: an in vivo study in the rat.

The influence of propranolol on surgical bleeding and hemostasis was studied in two different models in the normotensive rat. Propranolol was administered for 6 days subcutaneously and for 28 days orally. In both the tail and the muscle bleeding test the blood loss after the short-term as well as the long-term administration of propranolol was diminished as compared to control values. Highly significant differences were reached in the tail bleeding test. Previous studies have described the effect of propranolol on several constituents of the highly complex hemostatic process. Some of these effects enhance, others inhibit hemostasis. It is concluded that in the normotensive rat these hemostasis-enhancing effects are of greater importance than the inhibiting ones.

Development of hypertension in spontaneously hypertensive rats after gonadectomy: effects of secobarbital anesthesia on the blood pressure.

Male spontaneously hypertensive rats (SHR) were gonadectomized at an age of 5 weeks. Systolic blood pressure and heart rate were measured up till an age of 12 weeks in trained unanesthetized rats. The development of the hypertension and heart rate were not significantly affected by removal of the testes and epididymis or removal of the testes only. Kidney, adrenal and thymus weight did differ from the values in sham-operated rats. After the administration of secobarbital sodium, however, a significant lower blood pressure had been observed in gonadectomized rats compared with sham-operated rats. Significantly higher levels of secobarbital were detected in plasma and brain of gonadectomized SHR. It is concluded that gonadectomy does not effect blood pressure of SHR and that the previously reported retardation of development of hypertension in gonadectomized SHR is caused by the different effect of anesthesia on blood pressure of gonadectomized and sham-operated rats.

Increase in plasma renin activity, water intake and blood pressure following application and reapplication of a renal artery clip.

Application of a renal artery clip in rats with an undisturbed contralateral kidney caused a sustained increase in blood pressure and a transient rise of plasma renin activity and water intake. The response of blood pressure, plasma renin activity and water intake was augmented after reapplication of the clip to normotensive declipped rats (renal hypertensive rats, from which the clip had been removed 24h before the reapplication). The time-course of the changes of blood pressure, plasma renin activity and water intake were similar after the initial application as after reapplication of the clip. Administration of an inhibitor (SQ 14.225) of the converting enzyme abolished the increase in blood pressure and water intake after reapplication of the clip. These data indicate a critical role of renin in the rise of blood pressure and water intake after initial application of a renal artery clip as well as after reapplication of the clip to declipped rats.

Attenuated depressor response to arachidonic acid and prostaglandins in unclipped renal hypertensive rats.

1 In renal hypertensive rats (one-clip, two-kidney type) blood pressure returned to a normotensive level within 24 h after the removal of the renal artery clip (unclipping). 2 The decrease in blood pressure caused by intravenous administration of arachidonic acid, prostaglandin E2 and prostaglandin I2 was significantly reduced in these unclipped rats. 3 The hypotensive response to bradykinin and acetylcholine was the same in unclipped rats and in control rats. 4 Nephrectomy abolished the difference in blood pressure response to arachidonic acid and the two prostaglandins between unclipped and control rats. 5 An enhanced secretion of renin, as indicated by the absence of an increase in plasma renin activity, did not seem to be involved in the attenuated blood pressure response to arachidonic acid in unclipped rats.

Time course of the enhanced blood pressure response to reinduction of renal artery stenosis in unclipped renal hypertensive rats.

Moderate or severe hypertension was induced in rats by application of a clip 0.25 or 0.20 mm internal diameter) to the left renal artery leaving the contralateral kidney intact. Removal of the clip 6, 13 or 24 days after the induction of the hypertension was followed by a rapid decrease in blood pressure. A near normotensive level was reached after 2--6 h. Reapplication of the clip to the unclipped renal artery after 1 day caused an enhanced blood pressure response. The preoperative hypertensive levels were reached within 2 h. This enhanced response was related to the level of blood pressure before the removal of the clip. Lengthening the interval between removal and reapplication of the clip gradually reduced the enhanced response of blood pressure, which had disappeared 8 days after the removal of the clip. Reapplication of the clip to the contralateral renal artery was not followed by an enhanced response in rats with previous moderate or severe hypertension.