The effects of pH, fixatives and divalent ions on nucleoside diphosphatase (NDPase) and thiamine pyrophosphatase (TPPase) activities in the endophasmic reticulum (ER) and Gohgi apparatus (GA) were examined in adult and neonatal hepatocytes and other cell types in the rat. In liver cells TPPase and NDPase both have a similar localization in the rough ER, nuclear envelope and snnooth ER but (lifer in their pH optima; TPPase is most active at pH 8, NDPase at pH 7. TPPase in the GA, unlike its counterpart in the ER, is most active at neutral ph. high levels of NDI'ase activity are present in the GA of neurons, epididymis an(I other cells, l)Ut not ml hepatocytes. TPPase in the ER, but not the GA, is stimulated by the addition of adenosine triphosphate to the medium. These observations show that different conditions are required to demonstrate ER and GA (hipliosphatase activities. Whether separate enzymes or multiple configurations of a single protein are responsible for these activities cannot be determined by staining procedures.

The relationship of lysosomes to the vascular effects of hypertension and the possible modification of these effects by anti-inflammatory agents (methylprednisolone and aspirin), vitamin E, and estrogen were studied. Each of these agents was given to a group of hypertensive rats; untreated hypertensive rats and normotensive rats served as controls. Vessel wall morphology and dimensions of aortas from hypertensive rats were unaffected by treatment. Usual connective tissue accumulations seen in hypertensive vessels were suppressed to normotensive levels in the methylprednisolone-and estrogentreated hypertensive groups. Two lysosomal enzymes, acid phosphatase and Nacetyl-/3-d-glucosaminidase (NAGA), increased over normal levels in hypertensive vessels from 1.03 ± 0.08 (SE) to 2.04 ± 0.19 /imoles/aortic pair hour" 1 and from 1.10 ± 0.24 to 4.57 ± 0.38 /^moles/aortic pair hour" 1 for the respective enzymes. Normal enzyme levels in estrogen-treated hypertensive rats (1.14 ± 0.15 /^moles/aortic pair hour" 1 for acid phosphatase and 2.04 ± 0.44 /imoles/aortic pair hour" 1 for NAGA) and intermediate levels in methylprednisolone-treated hypertensive rats (1.35 ± 0.10 /tmoles/ aortic pair hour" 1 for acid phosphatase and 2.48 ± 0.54 /^moles/aortic pair hour" 1 for NAGA) were found. Other treated groups showed the usual elevations associated with hypertension. These group differences were also seen after cytochemical staining for lysosomal acid phosphatase and NAGA. The parallel changes in aortic connective tissue and lysosomal enzymes in hypertension and their modification by two drugs suggest that these events are related. KEY WORDSiV-acetylglucosaminidase aspirin elastin collagen acid phosphatase estrogen methylprednisolone vitamin E vascular smooth muscle

Renal peroxisomes are believed to be restricted to the proximal convoluted tubules. However, we have found particles in the ioop of Henle and distal convoluted tubule that resemble the peroxisomes of the proximal tubules in some respects. Although smaller in size (generally too small to be resolved in the bight microscope), they have a finely granular homogenous matrix and are delimited by a single unit membrane. Whether these are microbodies (peroxisomes) or dense bodies (lysosomes) cannot be determined solely on the basis of their fine structure. These bodies do not show acid phosphatase activity, indicating that they are not lysosomes. When incubated in a diaminobenzidine medium that demonstrates the peroxidatic activity of the peroxisomal enzyme catalase, the small bodies are reactive, suggesting that they are peroxisomes. This activity is blocked by 3-amino-i ,2 ,4triazole, an inhibitor of catalase.