Quantitative assessment of coronary arteriosclerosis in hypertensive rats.

Following Skelton's procedure with unilateral adrenonephrectomy, contralateral adrenal enucleation and application of 1% NaCl with the drinking fluid, genetically normotensive rats develop hypertension and a generalized arteriosclerosis, i.e. necrotizing hypertensive angiopathy. In the present study, the effect of high blood pressure was investigated in 13 Skelton hypertensive rats and 13 normotensive control rats. Systolic blood pressure was investigated by tail plethysmography over a period of 7 weeks. During the experiments, 3 of the Skelton rats died with final high blood pressure values, whereas all controls remained alive. Mean systolic blood pressure of the 10 surviving Skelton rats increased from 108 to 223 mm Hg. The control rats remained normotensive. Accordingly, heart weights of the hypertensives were higher than those of the controls (p = 0.0027). At the end of the experiment, arteriosclerosis was quantified by counting the heart arteries and arterioles with deposits of fibrinoid in the vascular wall in 10 histological cross-sections per heart. In the right ventricular wall of 6 of the 10 surviving Skelton rats, arteries and arterioles with deposits of fibrinoid in the vascular wall were detected. No such alteration was observed in the left ventricular wall or in the interventricular septum. About one third of the altered blood vessels showed fibrinoid necrosis. In contrast, the normotensive control rats had neither fibrinoid necrosis nor sclerotic arteries in corresponding sections of the hearts (p = 0.0052). The findings show that Skelton hypertension can be used as an experimental model for quantitative histological investigation of coronary arteriosclerosis in hypertensive rats.(ABSTRACT TRUNCATED AT 250 WORDS)

[Suppression of coronary sclerosis in hypertensive rats by calcium channel antagonists without lowering blood pressure]. / Suppression der Koronarsklerose hypertoner Ratten durch Kalziumantagonisten ohne Senkung des hohen Blutdrucks.

Following Skelton's procedure with unilateral adrenonephrectomy, contralateral adrenal enucleation and application of 1% NaCl with drinking fluid, normal rats develop hypertension and generalized severe arteriosclerosis within 7 weeks, experimental group I. Thereby the mean systolic blood pressure increased from 108 +/- 10 to 223 +/- 12 mm Hg, and 90 arteriosclerotic blood vessels could be counted in 100 histological sections (10 from each animal) of the hearts. Following Skelton's procedure and admixture of flunarizine with the food (40 mg flunarizine per kg for 8 weeks, started 1 week before the operation; mean plasma flunarizine value: 336 +/- 136 ng/ml at the end of the experiment), experimental group II, all rats developed hypertension too, whereby the mean systolic blood pressure increased from 109 +/- 10 to 214 +/- 16 mm Hg, but in contrast to experimental group I, only one artery with sclerosis could be observed in 100 comparable histological sections of the hearts. The untreated control rats, experimental group III, remained normotensive, and no arteriosclerotic blood vessels could be observed. The findings presented show that the calcium-antagonist flunarizine with the dosage used does not reduce hypertension, but almost completely suppresses hypertension-induced arteriosclerosis of the myocardial blood vessels without lowering the high blood pressure.

Pantothenic acid deficiency as a factor contributing to the development of hypertension.

In endemic pantothenic acid deficiency of some Japanese populations, increased occurrence of hypertension has been described. However, all attempts to produce hypertension experimentally by means of pantothenic acid deficiency have failed up to now. As a consequence, the observations made in Japan have largely been ignored. In this paper, pantothenic acid deficiency will be shown to be a factor in the experimental origin of hypertension due to adrenal regeneration.

[Development of hypertension and cataract in spontaneously hypertensive rats]. / Untersuchungen zur Hypertonie- und Kataraktentstehung bei spontan-hypertensiven Ratten.

The investigations were performed on 3 groups of untreated, spontaneously hypertensive Wistar rats of the Okamoto line. All the rats in Group I developed arterial hypertension within 16 weeks of birth and 33 percent of them developed cataracts within 22 weeks. Reserpine application suppressed hypertension and cataract development in all the animals in Group II. After unilateral adrenalectomy and contralateral adrenal enucleation (Group III), hypertension and cataracts developed in both treated and untreated animals; in the former, however, blood pressure was about 10 percent higher and cataracts developed about 6 weeks earlier than in the untreated rats. These findings support the hypothesis that arterial hypertension may be involved in cataract development.

[Occurrence and structure of accessory adrenal glands in Wistar rats]. / Uber Vorkommen and Struktur accessorischer Nebennieren bei der Wistar-Ratte.

In complete series of histological sections through the entire abdomen of one normal Wistar-rat, one untreated and two bilaterally adrenalectomized, spontaneously hypertensive Wistar-rats accessory suprarenal glands were found in each case. The detailed findings in the various groups of animals investigated were as follows: (1) In the normal animal 10 accessory suprarenal glands were present. They consisted of tiny aggregates of cortical cells and were surrounded by a thin layer of collageneous fibers. The diameters of the accessory suprarenal complexes were in the order of 0.3 mm. (2) In the untreated, spontaneously hypertensive rat three accessory suprarenal glands were found. However, in contrast to what was seen in the normal rat, these complexes were larger and had diameters of up to 1 mm. Some of these accessory suprarenal glands consisted almost exclusively of small, chromophobe cells, whereas in others a rim of such cells was seen to surround a central core of larger and more acidophile cortical cells. There were few and collapsed capillaries. (3) In the bilaterally adrenalectomized, spontaneously hypertensive rats three, respectively four, accessory suprarenal glands were found. They were situated in the retroperitoneum and partly within the adipose capsule of the kidney but never in the place of the exstirpated main suprarenal glands. In one case an accessory gland was found within the fibrous capsule of the kidney and seen to compress the renal parenchyma. In the bilaterally adrenalectomized animals the average diameters of the accessory glands were larger than in the other groups reaching values of up to 5 mm. At least in both animals one of the accessory glands had a diameter comparable to that of the normal suprarenal gland of an untreated animal. The capillaries were dilated and their number was increased in comparison to what was seen in the other groups. In certain regions the cortical tissue of the accessory glands had an appearance resembling that of zona fasciculata and reticularis.

Effect of fixation on the demonstration of neurophysin and "Gomori-positive" substances in neurosecretory granules of the rat hypothalamus.

Proteins reacting with neurophysin antibodies and "Gomori-positive" substances were demonstrated histochemically in hypothalamic neurosecretory material of normal and bilaterally adrenalectomized rats after two different fixations: a) picric acid-formalin (PAF) for 7 days at 37 degrees C; b) Bouin's fluid for 20 h at 4 degrees C. After PAF-fixation anti-neurophysin reactive neurosecretory granules are found in all parts of the supraoptico-hypophysial system and in the suprachiasmatic nucleus of normal and adrenalectomized animals. In the latter they can additionally be demonstrated in the outer layer of the median eminence. Amount and distribution of "Gomori-positive" substances correspond to those described for the immunoreactive material, except for the suprachiasmatic nucleus, in which the substances can not be detected; Following fixation in Bouin's fluid the immunohistochemical reactions are unchanged whereas the staining of "Gomori-positive" substances is remarkably impaired. The amounts of the substances demonstrable in the neural lobe are diminished and in the cells of the supraoptic and paraventricular nuclei as well as in both median eminence layers only traces of the substances are to be seen. The findings indicate that negative results in demonstrating "Gomori-positive" substances may be caused by inappropriate fixation and need to be controlled by immunohistochemical techniques.

Influence of sodium chloride on the amount of CRF-granules and "classical" neurosecretory material (NSM) in the neurohypophysis of bilaterally adrenalectomized rats.

Bilaterally adrenalectomized female SPF Wistar rats were given tap water containing various concentrations of sodium chloride to drink ad lib. After a survival period of 14 days the animals were killed by perfusion-fixation. Their brains were removed, fixed in picric acid formalin solution and embedded in Paraplast. Serial sections of median eminence and hypophysial posterior lobe were cut and stained with crotonaldehyde-fuchsine. In the stained sections the amount of CRF-granules visible in the external zone of the median eminence, and the amount of "classical" neurosecretory material (NSM) occuring in the internal zone of the median eminence and in the posterior lobe of the hypophysis were estimated. After administration of drinking solutions to which 0%-1% sodium chloride were added, the amount of CRF-gr anules increased with increasing NaCL uptake, whereas the amount of "classical" NSM was not changed. Application of tap water containing 2% NaCl led to a marked decrease in the amount of "classical" NSM but did only slightly impair the amount of CRF-granules. From the findings it is concluded that 1. following bilateral adrenalectomy administration of sodium chloride inhibits the secretion of CRF-granules; 2. CRF-granules and "classical" NSM, although histochemical identical, have different functional significances; 3. the mechanisms regulating the secretion of CRF-granules are different from those controlling the release of "classical" NSM.

Simultaneous changes of the perivascular contact area and HIMOT activity in the pineal organ after bilateral adrenalectomy in the rat.

In the pineal organ of the female rat, proportional changes in the area of contact of pinealocyte processes and glial processes with the perivascular space were found after bilateral adrenalectomy. The contact area was evaluated by measuring the length of pinealocyte and glial cell membranes directly abutting on the basal lamina. In the normal female rat, 40% of the contact area is occupied by pinealocyte and 60% by glial cell processes. Fourteen days after bilateral adrenalectomy, this proportion is reversed. In addition, cell counts demonstrate that more pinealocytes gain access to the pericapillary space due to the experimental conditions. In order to prove whether or not these results indicate an increase of pineal endocrine activity, the melatonin-forming enzyme hydroxyindole-O-methyltransferase (HIOMT, E.C. 2.1.1.4) was assayed. After bilateral adrenalectomy the HIOMT activity was found to significantly increase.

Histochemical and immunohistochemical properties of the CRF-granules and other "Gomori-positive" substances of the rat.

In adrenalectomized rats, histochemical and immunohistochemical properties of the following secretion products have been investigated: 1. CRF-granules in the outer layer of the median eminence; 2. neurosecretory material (NSM) in the supraoptico-hypophysial system of the hypothalamus; 3. secretory granules in the TSH-cells of the anterior lobe of the hypophysis; 4. secretory granules in the ependymal cells of the subcommissural organ (SCO); 5. beta-cell-granules in the islets of Langerhans in the pancreas. All these substances are characterized by their stainability with the so-called "Gomori method". The experiments have included studies into: a) the extractability of the substances by various solvents; b) the digestability of the substances by pepsin or trypsin; c) their histochemically detectable content of disulfide groups, arginine and periodic acid-Schiff (PAS) reactive carbohydrates; d) their reaction with porcine-neurophysin-II-antibodies. All substances exhibited a positive reaction for disulfide groups. Based on their solubility properties, their resistance to pepsin or trypsin, their respective content of PAS-reactive carbohydrates and their failure to react with anti-neurophysin serum the "Gomori-positive" granules in TSH-, SCO- and pancreatic beta-cells can be distinguished from one another and from CRF- and neurosecretory granules. In contrast, CRF-granules and NSM showed identical properties. Taking into consideration data from the biochemical and histochemical literature, the present findings suggest that CRF-granules and NSM consist of closely related biochemical substances.