S. Porta

Albumin as one-way transport vehicle into sites of inflammation

Intravenously injected Evans blue combines with albumin. The resulting complex appears in the inflammatory exudate that collects in Sephadex G 200 subcutaneously injected into rats. A comparison between the concentrations of albumin and Evans blue in the blood and in the inflammatory exudate shows that the life-span of albumin in the Sephadex is drastically reduced. After decomposition of albumin, the combined Evans blue is liberated, accumulates in the Sephadex and, after 24 h, attains concentrations higher than in the blood. The experiment is a plausible model for transport and deposition of albumin-bound drugs into and at sites of inflammation.

Long-term application of some catecholamines elevates levels of other catecholamines in rats

Male Sprague-Dawley rats were treated during 20 h with subcutaneously implanted tablets (controlled release systems) containing either adrenaline (A), noradrenaline (NA), isoprenaline (ISO) or just placebos. Levels of the exogenously administered catecholamines (CA) in plasma and liver homogenate were significantly higher than in controls throughout the test time. During NA application endogeneous A and dopamine (DA) plasma values rose considerably, while ISO application enhanced endogenous NA and A levels. Adrenaline application increased NA and DA plasma levels. Several possibilities for this phenomenon are discussed, and it is concluded that previous papers dealing with observations of long term action of CAs should be reevaluated unless the influence of the artificially given CA on the elevation of endogenous CAs has been already taken into consideration.

The influence of a permanent isoproterenol (ISO) application on the dynamics of the Sephadex inflammation.

The influence of Isoproterenol on the number of the different types of white blood cells appearing during the course of the Sephadex inflammation was investigated in rats. Isoproterenol treatment causes a decrease of the number of the immigrating neutrophils within the first two days and an increase of the lymphocytes during almost the entire experiment. A sudden decrease of the number of these cell types, indicating a massive cell destruction, was followed by immigration of eosinophilic granulocytes after 24 hrs. Isoproterenol accelerated and augmented this immigration. We conclude, that perishing neutrophils and lymphocytes produce or mediate the production of factors which attract eosinophils and moreover that Isoproterenol enhances the production or the effect of these factors. The mechanism underlying this enhancement is not known. We suppose a specific beta-adrenergic influence, because we could not reproduce this increasing effect with adrenaline.

Salivary gland enlargement as a test for a new way of permanent isoproterenol application

Low doses of isoproterenol, given permanently by a new application-method, show the same effects on salivary-gland enlargement of rats throughout approx. 6 days than 10fold higher concentrations given by previous workers as single daily injections.

Peculiar long-term effects of catecholamines and their blockers in rats on insulin, glucose and pancreas*

To be able to study the long-term effects of moderately enhanced catecholamine levels in rats, we developed subcutaneously implantable retard systems, granting a linear output of various agents throughout the test time. Adrenaline application leads to hyperglycemia without elevation of serum immune-reactive-insulin (IRI) during 20 h of uninterrupted adrenaline (A) action. This we call an A-induced diabetes like reaction. It could be completely abolished by simultaneous application of low phentolamine (Regitin) doses. Simultaneous application of propranolol (P) gradually diminished blood glucose levels from about 200 mg/dl after 6 h to 120 mg/dl after 20 h. Since here insulin levels are uniformly low, decline of blood glucose could not be due to enhanced insulin-action. The moderate hyperglycemia after 6 h isoprenaline (ISO)-treatment alone goes with a hyperinsulinemia at the same time. Obviously this hyperinsulinemia cannot cope with the increased blood glucose probably due to enhanced liver-glycogenolysis by intact alpha-action. Later on insulin--despite of beta-action on pancreas--declines strictly proportional with diminishing blood-glucose-levels. A comparison between the action of catecholamines and their blockers showed that alpha-blockers tend to diminish blood glucose levels by two independent ways, namely by the inhibitory action on pancreas and the inhibitory action on liver glycogenolysis.

Changes in blood catecholamines, insulin, corticosterone and glucose during the course of the Sephadex inflammation.

During an acute inflammation, the blood levels of noradrenaline, dopamine and insulin increase uniformly until the fourth day, then reach a climax which for dopamine is above the norm, while the suppressed levels of noradrenaline and insulin approach the norm. All values decrease on the fifth day (end of the experiment). Glucose behaves inversely, showing a minimum on the fourth day. Corticosterone displays two peaks, on the first and fourth days. The adrenaline level differs distinctly from these patterns: it is elevated on the second, fourth and fifth days. By releasing each catecholamine independently, the organism can possibly influence the course of the inflammation.

Antiinflammatory substances appearing during an acute inflammation and the alteration of their properties by isoproterenol (ISO). An in vivo investigation in rats.

It could be demonstrated that antiinflammatory substances appear during the course of an acute inflammation. The inhibition of leucocyte immigration into the site of inflammation (caused by Sephadex) was taken as criterion for the antiinflammatory property. The highest quantity or effect of the antiinflammatory substances was found on the 3rd day after inflammation has started. Not only the absolute number of cells but also the composition of the cellular exudate (compared with a fresh inflammation) was changed: The percentage rate of the neutrophils was reduced, whereas the portion of the eosinophils and the lymphocytes was increased. A permanent ISO application on the animals altered the quantity of the composition of these substances, in consequence of which the immigration of eosinophils and lymphocytes was promoted. The reaction of the neutrophils was unaffected.

Inhibition of adrenalin depletion in hypoglycaemic rats following permanent adrenalin application by depot capsule

Chronic treatment of rats with adrenalin by means of a subcutaneous depot capsule (cont. 40 mg dry adrenalin/HCl, Merck, ca. 10 mg ascorbic acid and ca. 0.4 ml 0.9% NaCl, and sealed with a dialysis membrane to provide constant adrenalin output) leads after a primary hyperglycaemic phase to hypoglycaemia. At the onset of hypoglycaemia the adrenalin contents of the suprarenal glands decrease to levels of about one third of their normal state. Simultaneous glucose infusions by intraperitoneal depot capsules prevent hypoglycaemia as well as adrenalin depletion. The fact that adrenalin depletion does not always correspond with blood sugar levels below 80 mg/dl and that this depletion could be prevented by glucose infusions altogether seems to provide a strong hint that the mentioned depletion is due to hypersecretion and not to the blocking of adrenalin synthesis. If is true, then there must be no direct negative feed-back system between adrenalin secretion and its extraglandular level.

The long-term influence of isoproterenol (ISO) retard tablets on the course of an acute inflammation.

Rats were exposed for 21 d to Isoproterenol (ISO) applied by subcutaneously implanted retard tablets. ISO causes a rise in the number of lymphocytes at the site of inflammation (injected sephadex) until the tenth day. The reaction of the connective tissue is moderately enhanced. The weight of the salivary glands is constantly elevated,and the weight of the hearts increases in a linear pattern until the end of the experiment. Neither in test nor in control animals is there any correlation between the number of white cells in the blood and their appearance at the site of inflammation.

Adrenaline application by controlled release system shows that it does play a physiological role in glycogenolysis

In a frequently cited paper Sokal , Sarcione and Henderson (1964) doubted the physiological glycogenolytic role of adrenaline (A). By using isolated perfused rat livers, they found adrenaline to be effective at doses higher than 140 ng/ml while a mere tenfold increase in glucagon leads to expressed glycogenolysis. Our in vivo experiments carried out with controlled release systems for adrenaline show that marked glycogenolysis takes place at an adrenaline serum level of not more than 20 ng/ml while endogenous glucagon levels do not differ from controls. We think, that the reason for those controversial results lies in the fact that Sokal , Sarcione and Henderson (1964) diminished the glycogenolytic action of adrenaline by blocking its alpha-component for the reason of an easier perfusion, and they further diminished its glycogenolytic action by omitting corticosterone, which is well known for its permissive role in adrenaline induced glycogenolysis in vivo.