Pulmonary vascular changes in young and aging rats exposed to 5,486 m altitude.

Young (YNG) and middle-aged (MA) male rats were exposed to 5,486 m for durations ranging from 1 to 42 days to determine the effect of age on the progression of polycythemia, right ventricular hypertrophy (RVH), lung vascular muscularization, and pulmonary vascular responsiveness. Other rats were exposed for 42 days at 5,486 m and were then allowed to recover at 1,520 m for periods up to 42 days. The progression and subsequent regression of polycythemia and RVH with altitude exposure were similar for YNG and MA rats. However, YNG rats exhibited vascular muscularization during the altitude exposure, characterized by hypertrophy of smooth muscle cells, whereas MA rats exhibited little or no change in vascular morphology. Lungs from both altitude-exposed YNG and MA rats exhibited blunting of acute hypoxic pulmonary vasoconstriction upon exposure to 5,486 m, with more severe blunting apparent in MA rats. Pressor responses to angiotensin II (AII) were potentiated in lungs from high altitude rats, particularly in the YNG rats, and this increased responsiveness persisted during the recovery period. A positive correlation was found in YNG rats between the degree of vascular muscularization and the pressor response to AII, suggesting that increased muscle mass was partially responsible for the potentiated AII responses. However, MA rats did not exhibit the same correlation for AII, and neither YNG nor MA rats exhibited increased responsiveness to 5-hydroxytryptamine. The results indicate that age influences the morphologic responses to altitude exposure and vascular responsiveness to AII, but does not affect the polycythemic response or the degree of RVH.

Pharmacokinetics of zinc tannate after intratesticular injection.

Forty-eight sexually mature male rats were injected intratesticularly with either 1, 3, or 6 mg zinc tannate (Kastrin) or with saline (as control). Zinc localized only in low concentration in primary spermatocytes and could not be detected in spermatogonia, Sertoli cells, spermatids, or spermatozoa. Forty-eight hours after injection of 1 mg Kastrin, zinc was accumulated in the spermatogonia and primary spermatocytes while, after injection of 3 mg, zinc was preferentially localized in Sertoli cells and spermatids; however, zinc was observed in the spermatids and spermatozoa 48 h after injection with 6 mg, and germ cells lost their identity and were fragmented after 1 week.

Chemical sympathectomy and serotonin inhibition reduce monocrotaline-induced right ventricular hypertrophy in rats.

Young male rats were administered monocrotaline (40 mg/kg, s.c.) either after chemical sympathectomy with 6-hydroxydopamine (6-OHDA, 100 mg/kg), after serotonin synthesis inhibition with p-chlorophenylalanine (PCPA, 500 mg/kg), or after saline injection. Monocrotaline rats exhibited a loss of body weight, marked right ventricular hypertrophy (RVH), increased pulmonary vascular muscularization, but no change in left ventricular weight or hematocrit at 20 days post-monocrotaline. Pretreatment with 6-OHDA or PCPA reduced the degree of RVH; however, neither 6-OHDA nor PCPA pretreatment prevented or reduced the pulmonary vascular muscularization associated with monocrotaline. Control, 6-OHDA-, and PCPA-treated rats exhibited only changes in ventricular weights associated with changes in their body growth. Thus, the sympathetic nervous system and serotonergic mechanisms seem to be involved in the development of monocrotaline-induced right ventricular hypertrophy, but are not responsible for the pulmonary vascular lesion.

Density and ultrastructure of mast cells in lung vessels of aging rats exposed to and recovering from chronic hypoxia.

A decrease in pulmonary vascular responsiveness in aging animals during exposure to chronic hypoxia has been previously reported; however, morphological documentation is lacking. Lungs from young (3-5 months) and aging (12-14 months) Sprague-Dawley rats, exposed to and recovering from chronic hypoxia, were morphometrically analyzed at the light-microscopic level for changes in perivascular mast cells, and at the electron-microscopic level for cellular alterations. While young rat lungs showed proliferation of mast cells around elastic and muscular pulmonary arteries and arterioles, perivascular mast cell density in lungs of aging rats was significantly greater than in young rat lungs. At the ultrastructural level, perivascular mast cells in aging hypoxic rats showed numerous profiles of cellular extensions that contained remnants of discharged secretory vesicles. The results suggest that increased proliferation of perivascular mast cells as well as increased secretory activity of vasoactive substances in aging animals might represent a humoral determinant of the hyporesponsiveness of pulmonary vessels that occurs with increasing age during chronic hypoxia.

Changes in pulmonary alveolar macrophages in rats exposed to oxides of zinc and nickel.

Pulmonary alveolar macrophages (PAM) from rats exposed to a single dose of ZnO or NiO showed distinct changes in size and ultrastructure. ZnO exposure brought about considerable reduction in the size of the cells, which can be distinguished into two types of macrophages. The macrophages contained a prominent nucleolus, several primary and secondary lysosomes, membrane formations, electron dense structures, and small dense mitochondria. In addition, electron dense and membrane bound structures were seen in the interstitial macrophages and in the intercellular spaces. NiO exposure induced hypertrophy and hyperplasia of the alveolar walls. The macrophages contained invaginated bizarre-shaped nuclei, pigment aggregations, and membrane bound structures. The results seem to suggest that after a one week recovery period following injections with ZnO and NiO, ZnO-related accumulations were transferred from alveolar to interstitial macrophages, however NiO-associated structures were contained within the alveolar macrophages.

Effect of LHRH on cyproterone-acetate-injected adenohypophyses of castrated mice.

Luteinizing hormone releasing hormone (LHRH)-treated adenohypophyses from castrated, cyproterone acetate-injected adult male mice were studied with transmission electron microscopy (TEM). LHRH-treated luteinizing hormone (LH) gonadotrophs (types a and b) in castrated mice showed accumulation of secretory granules at the capillary pole, dilated Golgi apparatus and extensive rough endoplasmic reticulum (RER) profiles. Following treatment, granular content in LH type-a gonadotrophs was decreased and profiles of secretory granules were seen in the intercellular and perivascular spaces. Some RER cisternal hypertrophy was noted, and the Golgi apparatus was dilated. In LH type-b gonadotrophs there were secretory granules lined along the plasma membranes, several lysosomes, multivesicular bodies, and short RER profiles. LHRH stimulated secretory granules release of LH gonadotrophs in cyproterone-acetate-treated castrated mice. Cyproterone acetate may have blocked hypothalamic LHRH stimulation of pituitary LH gonadotrophs.

Fine structural changes in pulmonary veins of chronically hypoxic mice.

The pulmonary veins of male Swiss albino mice, exposed to simulated high altitude (380 mm Hg) for four weeks were studied for structural alterations. Endothelial cells contained invaginated nuclei and an accumulation of vesicles on the adluminal surfaces. In the subendothelial region, cells which contained filaments and dense bodies were noted. Increased muscular contraction, evidenced by decrease in the width of the I-band of the sarcomere, caveolae formation, sarcolemmal invaginations, and glycogen deposition were the most evident changes in the cardiac muscle layer. These alterations were interpreted as possible morphologically adaptive changes of pulmonary venous pulmonary vasoconstriction in response to increased metabolic demands as a result of changes in pulmonary hemodynamics with chronic hypoxia.

Glycogen localization in pulmonary vascular smooth muscle of chronically hypoxic rats.

The pulmonary trunk, muscular arteries, and arterioles of male Sprague-Dawley rats exposed to simulated high altitude hypoxia (380 mm Hg) for six weeks were studied for glycogen localization. As early as three days exposure time, glycogen particles were mobilized in the smooth muscle cells of muscular arteries and arterioles. Weekly sacrifice of animals showed increasing preferential accumulation of glycogen, near the sarcoplasmic reticulum, in the subsarcolemmal region, adjacent to micropinocytotic vesicles, and near the mitochondria in the smooth muscle cells of muscular arteries and arterioles. However, in the smooth muscle cells of the pulmonary trunk and newly muscularized vessels (arteries and arterioles), glycogen storage was not readily noted. These results suggests that the vascular energetics responsible for maintaining the pulmonary hypertensive state differ depending on the class of vessel. Also the muscular pulmonary arteries and arterioles which exhibited the greatest change in glycogen metabolism, may be primarily responsible for the maintenance of pulmonary hypertension.

Ultrastructural changes in rat alveolar macrophages exposed to oxides of copper and cadmium.

The morphological effects of single intratracheal injections of copper oxide (CuO) and cadmium oxide (CdO) (5 mg) on rat alveolar macrophages were studied. Rats sacrificed after a one week recovery period showed distinct morphological changes induced by CuO and CdO. Copper oxide induced hypertrophy of both the alveolar macrophages as well as the epithelial lining. The macrophages contained polymorphic nuclei with margination of the chromatin, crystalloid-like inclusions, concentric and parallel lamellar structures, lattice formationa and degenerative membranous structures. After CdO treatment, a slight increase in the number of alveolar macrophages and an attenuated thickening of the epithelial wall were noted. Two types of macrophages were identified: one type was large in size, with numerous vacuoles, electron dense aggregations, phagocytized mitochondria and fragmented chromatin. The other type was smaller in size, with fewer vacuoles, a distinct rough endoplasmic reticulum, mitochondria, and a highly convoluted plasma membrane. The results were suggestive of degenerative morphological alterations due to CuO and CdO treatments which were incompatible with normal macrophage function.

Altered vascular responsiveness in isolated perfused lungs from aging rats.

Systemic vascular hyporesponsiveness has been well documented in aged rats, but a similar decreased vasoreactivity of the pulmonary vasculature has not been reported. Isolated lungs from young (3-5 months) and middle-aged (12-14 months) rats were perfused with whole blood and challenged alternately with alveolar hypoxia, angiotensin II, and 5-hydroxytryptamine. Hypoxic pulmonary vasoconstriction was less in the aging rats during both 5-min and 10-min hypoxic exposures. Likewise, log-dose response curves for angiotensin II and 5-hydroxytryptamine were right-shifted in the aging rats, indicating decreased responsiveness to the vasoactive agents. Since the vascular responses to all three vasoconstrictors were lower in the older animals, a generalized pulmonary vascular hyporeactivity with advancing age is suggested.

Effect of cyproterone acetate on adenohypophysis of castrated mice.

Pituitaries from castrated male mice injected with cyproterone acetate were examined ultrastructurally. LH gonadotrophs showed two types: (a) those containing a dilated RER, a hypertrophied Golgi, and decreased granular content; and (b) those presenting an electron lucent cytoplasm and a nonhypertrophied RER. Following cyproterone acetate treatment both LH cell types showed increased RER cisternal hypertrophy and absence of Golgi membranes. In LH type (a) gonadotroph-increased granular content was noted. No detectable alterations were noted in FSH gonadotrophs following cyproterone acetate treatment. Cyproterone acetate may have stimulated the synthesis of the protein component but inhibited the incorporation of the carbohydrate moiety and LH release.

The effect of cyproterone acetate on the mouse adenohypophysis. II. Gonadotrophs and somatotrophs.

The adenohypophyses of adult male C57BL/6J mice pituitaries injected with cyproterone acetate for four weeks were examined with the electron microscope. The gonadotrophs showed an accumulation of the hormone-containing granules, and a noticeable decrease in the amount of rough endoplasmic reticulum. The somatotrophs exhibited proliferated profiles of rough endoplasmic reticulum, hypertrophied Golgi apparatus, and a slight decrease in the GH-containing granules. It is believed that the cyproterone acetate may have inhibited synthesis and release of the gonadotropins, and may have stimulated the GH -producing cells through the progestational activity of this antiandrogen.

Effect of cyproterone acetate on mouse adenohypophysis. I. The adrenocorticotrophs.

The adenohypophyses of adult male C57BL/6J mice pituitaries injected with cyproterone acetate for four weeks were examined with the electron microscope. The adrenocorticotrophs of the adenohypophysis showed an absence of the 200-nm granules that were lined along the plasma membrane, a decrease in profiles of rough endoplasmic reticulum, sparse distribution of ribosomes, and flatten Golgi membranes. It is believed the antiandrogen cyproterone acetate inhibited ACTH synthesis and release and that this was responsible for adrenocortical atrophy.

Effect of cyproterone acetate on structure of adrenal cortex in hypophysectomized, ACTH treated mice.

Hypophysectomized adult male C57BL/6J mice injected with 0.08 mg/g of cyproterone acetate showed large aggregates of cellular lipid as well as nodular formations in the zona fasciculata of the adrenal cortex. Daily ACTH injections (10 IU) reversed the atrophic changes noted above. At the ultrastructural level, the zona fasciculata and zona reticularis cells exhibited decreased cellular lipid content, proliferated profiles of rough endoplasmic reticulum, an increase in polyribosomes, and an active Golgi apparatus. It is believed that cyproterone acetate inhibited adrenocortical steroidogenesis by interfering with pituitary release of ACTH.

Effect of castor oil and benzyl benzoate used as a vehicle for antiandrogens on the adrenal cortex.

The use of benzyl benzoate as a vehicle constituent in administering cyproterone acetate caused morphological changes detectable at the ultrastructural level in the adrenal cortex. Xastor oil and benzyl benzoate in a 4:1 ratio caused intracellular as well as intercellular changes. In the zona fasciculata there were alterations in mitochondrial shape, size, and matrix. Intercellular changes affected the morphology of macrophages in the zona fasciculata and zona reticularis. It is believed that the castor oil and benzyl benzoate vehicle caused stress-induced changes.

The innervation of the mouse adrenal cortex.

The fine structure of the mouse adrenal cortex was examined with the electron microscope for the presence of neural elements. Several axon terminals containing mostly clear vesicles (60 nm) were noted in the vicinity (250 nm) of the capsular fibroblasts. In the subcapsular region, myelinated as well as unmyelinated fibers were commonly found. Preterminal and terminal axons were also found in close relationship to the parenchymal cells in the zona glomerulosa. Nerve bundles were the most common neural elements in the zona fasciculata. In the zona reticularis axon terminals containing both clear (60 nm) and dense core (120 nm) vesicles were seen in close proximity (30 nm) to parenchymal cells. Although this study did not delineate the type of fibers involved, the axon terminals resemble those of autonomic nerves. This study demonstrates innervation of the mouse adrenal cortex, thus corroborating similar reports by others in different species.

Effect of cyproterone acetate on the structure of the adrenal cortex.

Adult male C57 BL/6J mice injected with 0.08 mg/g of cyproterone acetate showed an increase in cellular lipid content in the zona fasciculata and zona reticularis of the adrenal cortex. In the perimedullary region, densely staining cells aggregated to form scattered nodules. At the ultrastructural level, in the zona glomerulosa and zona fasciculata the number and size of lipid droplets increased. An apparent decrease in mitochondrial number and size and a noticeable diminution in the amount of smooth endoplasmic reticulum were also noted in the zona fasciculata. It is suggested that cyproterone acetate may have blocked steroid synthesis and increased adrenal cholesterol deposits.

Effect of cyproterone acetate on adrenal cortex of castrated mice.

Castrated adult male C57BL/6J mice displayed a wide perimedullary zone (secondary X-zone) whose cells were characterized by proliferated rough and smooth endoplasmic reticulum and elongated mitochondria with lamellar cristae. Castrated mice which received 0.08 mg/g of cyproterone acetate showed a much inhibited secondary X-zone at the light microscopic level, while at the ultrastructural level the perimedullary cells lacked the proliferated rough and smooth endoplasmic reticulum as well as the elongated mitochondria. Cyproterone acetate may inhibit the steroidogenic parameters of the androgen-producing cell population of the adrenal cortex without testicular mediation.