Intracerebroventricular angiotensin II increases arterial blood pressure in rhesus monkeys by stimulation of pituitary hormones and the sympathetic nervous system

Intracerebroventricular injections of angiotensin II in anesthetized rhesus monkeys increase systemic blood pressure and heart rate. These effects are accompanied by an increase in plasma ADH, cortisol, adrenaline and noradrenaline. Angiotensin II may participate in central mechanisms of blood pressure regulation by its stimulatory effect on the sympathetic nervous system, on ADH and on ACTH release in primates.

[Vessel structure and blood supply of free skin transplants in animal experiments in relation to their vessel supply]

In the total abdominal island skin flap of the rat based on both epigastric vessels in the groin, postoperative development after arterial or venous or complete division of the neurovascular bundle was documented. Photographic documentation, planimetry of the surviving skin area were used as methods together with evaluation of the blood supply of the flaps by Xe-133 clearance. The resulting new architecture of vessels was shown photomacroscopically by Indian ink injection. The function of arterial inflow and venous outflow was shown by microangiographical fluorescent methods. Hence, it was possible to combine special operation methods with definite new vessel structures, typical necrotic areas and postoperative mean value clearance results. Due to the difference of the xenon clearance results in individual cases, this method proved incapable of giving a safe prognosis on the survival of the special flap. Fluorescent microangiography pointed to the type of surgery which had been selected, and allowed functional evaluation of the blood supply of the flap.

Are aminosugars ototoxic?

The ototoxicity of the kanamycin fragment 3-amino-3- deoxy-D-glucose (3-aminoglucose, kanosamine), was investigated by perilymphatic perfusion in the guinea pig. Concentrations of 10 or 28 mM of this compound had no effect on cochlear microphonic potentials (CM), contrasting with previous observations (Owada 1962). Kanamycin at 1 mM decreased CM significantly under otherwise identical conditions. The action of kanamycin was at least partially reversible.

Brain angiotensin II stimulates release of pituitary hormones, plasma catecholamines and increases blood pressure in dogs

1. The mechanisms of central angiotensin II blood pressure effects in conscious dogs on normal or sodium-deficient diets were examined. 2. The biosynthesis of brain angiotensin II in cerebrospinal fluid from its local precursor angiotensinogen was induced in vivo by injection of 0.5 unit of hog kidney renin through a chronically implanted cannula into the third brain ventricle in conscious dogs. 3. Intracerebroventricular administration of renin induced an increase of arterial blood pressure and a marked drinking response under both dietary regimens. Sodium restriction had no effect on the magnitude of the central angiotensin pressor response. 4. Plasma concentrations of renin and angiotensin II decreased, and plasma antidiuretic hormone, noradrenaline, adrenaline and corticosterone increased, in both groups of dogs. 5. Simultaneous intraventricular administrations of captopril with renin inhibited the central renin effects. Intracerebroventricular injections of [Sar1, Val5, Ala8] angiotensin II alone increased plasma renin and angiotensin II concentrations. 6. It is concluded that endogenous brain angiotensin II participates in central mechanisms of blood pressure regulation by the stimulation of the release of antidiuretic hormone, adrenocorticotrophic hormone, adrenaline and noradrenaline.

Effects of modern loop diuretics on the inner ear a quantitative evaluation using computer technics

The effects of some modern high ceiling loop diuretics on the guinea-pig's inner ear are tested. Short-time experiments are run registrating the cochlear microphonic potentials (CMP) before and after i.v. bolus injections of a diuretic. A 100-point matrix program is performed by automatic sampling of the CMPs after stimulating by five frequencies at 20 sound pressure levels each. Data can be plotted in different scales within 10 min after the end of a whole-day experiment. The data are on-line processed by a IBM 1800 computer.

Blood pressure response to central and peripheral injection of angiotensin II and 8-C-phenylglycine analogue of angiotensin II in rats with experimental hypertension

1. We have compared the effect of central and peripheral administration of angiotensin II and (1-succinamoly-5-valine-8-phenylglycine)angiotensin II on blood pressure of male conscious unrestrained rats with normal blood pressure, and with spontaneous hypertension or chronic renal hypertension. 2. After central and peripheral injection of angiotensin II all rats exhibited a significant dose-related increase in blood pressure. 3. Administration of the analogue was without effect in normotensive rats. Ten-weeks-old rats with spontaneous hypertension showed a significant blood pressure decrease after central injection, but an increase after peripheral injection. This centrally induced decrease could not be observed in spontaneously hypertensive rats 14 weeks old. In these animals the analogue increased the blood pressure. In rats with chronic renal hypertension in contrast to peripheral injection, central administration decreased the pressure significantly. 4. Plasma renin activity was not changed after central injection of the analogue in normotensive rats. 5. These observations suggest the participation of the intrinsic brain isorenin-angiotensin system in central blood pressure regulation in these forms of experimental hypertension.

[Clofibrate treatment of diabetics with hyperproteinemias (author's transl)]

The effect of a six weeks clofibrate treatment on lipid metabolism was investigated in a collective of 38 constantly maladjusted elderly diabetics with an average of 30% overweight and various forms of hyperlipoproteinemias. Clofibrate produced a significant lowering of the mean triglyceride and cholesterol levels, whereas no such effect was observed in an untreated control group. Related to the various types of hyperlipoproteinemia (IIa, IIb and IV), the group treated with clofibrate showed a rate of normalization of nearly 50%, while the rate of improvement in the untreated control group was 10%.

[Evoked response audiometry of the guinea pig before and after drop in hearing induced by furosemid (author's transl)]

Using particular surface electrodes evoked response audiometry (ERA) can be applied to small laboratory animals without any sedation or anaesthesia. In addition to other methods we have studied in this way the influence of extreme doses of Furosemid on the guinea pig inner ear. 6-20 mg Furosemid per 100 g of bodyweight (about 100 times the human therapy dose) were applicated i.v. within 5 min resulting in a drop of hearing immediately. For the anaesthesized animal the cochlear microphonic potentials (CM) decrease simultaneously, indicating Furosemid to act at the inner ear itself. By both methods recovery of inner ear function is seen to start about 10 min later according to the little biological half life of Furosemid. As being restricted in respect of time for the CM-measurements we are sure about reversibility only by the ERA-method.

[The radiofibrinogen test in differential diagnosis of fresh deep venous thrombosis]

The radio-fibrinogen test is a simple and sensitive method for diagnosing deep vein thrombosis. Intravenously administered radioactive labelled fibrinogen is incorporated as radioactive fibrin in freshly developing thrombi, and such labelled thrombi may be detected on the body surface with nuclear medical equipment. Homologous iodine 125 labelled fibrinogen is chiefly used since it is known not to transmit viral hepatitis. The weak gamma emittor 125-I allows the use of a portable scintillation detector rate meter with an easily moved measuring device. This bedside method does not involve discomfort for the patient. The correlation between ascending phlebography and the radioactive fibrinogen test is more than 90 percent. The radiofibrinogen test may be used to study thromboembolic diseases, to evaluate drugs for prevention of thromboembolic complications and to confirm clinically suspected fresh deep vein thrombi. Details of the method as used in several thousand measurements are given.