Polyamines and NMDA receptors modulate pericapillary astrocyte swelling following cerebral cryo-injury in the rat.

Four hours following cryo-injury rat cerebral pericapillary astrocytes from the perilesional area were markedly swollen occupying 17% of the pericapillary space as compared to 11% in sham operated controls. Ornithine decarboxylase activity and polyamine levels were increased over sham controls. The astrocytic swelling, the percentage of the pericapillary space occupied by astrocytic processes, and polyamine levels were reduced to near control levels by the following: (1) alpha-difluoromethylornithine; (2) Ifenprodil; and (3) MK-801. alpha-Difluoromethylornithine is a specific inhibitor of ornithine decarboxylase, Ifenprodil is an inhibitor of the polyamine binding site on the n-methyl-d-aspartate receptor, and MK-801 is an antagonist to n-methyl-d-aspartate binding to the n-methyl-d-aspartate receptor. Addition of putrescine, the product of ornithine decarboxylase activity, reversed the effect of alpha-difluoromethylornithine and restored the pericapillary swelling. Putrescine did not affect the MK-801-induced reduction in pericapillary astrocytic swelling. Therefore, polyamines and the n-methyl-d-aspartate receptor modulate excitotoxic responses to cryo-injury in pericapillary cerebral astrocytes.

Polyamines mediate coronary transcapillary macromolecular transport in the calcium paradox.

This study addresses the role of polyamines and their rate limiting enzyme, ornithine decarboxylase in regulation of macromolecular transport of two macromolecules, fluorescein and horseradish peroxidase, across coronary capillaries. Rat hearts were isolated and retrogradely perfused through the aorta (Langendorff method), stabilized by 10 min perfusion with Krebs-Henseleit medium containing Ca2+, followed by 5 min perfusion with Krebs-Henseleit medium without Ca2+ and an additional 30 s to 2 min with Krebs-Henseleit medium containing 1 mg/ml horseradish peroxidase. alpha-Difluoromethylornithine, the only known function of which is inhibition of ornithine decarboxylase, and putrescine were added as needed. Perfusion with Krebs-Henseleit medium without Ca2+ caused a two-fold increase in fluorescein transport but a decrease in horseradish peroxidase transport. Reperfusion with Krebs-Henseleit medium caused a four-fold increase in fluorescein transport and a ten-fold increase in horseradish peroxidase positive intraendothelial cell vesicles over control values. alpha-Difluoromethylornithine inhibited these increases and putrescine negated the alpha-difluoromethylornithine effect. Other morphological measures of horseradish peroxidase transport and associated membrane activities including modulation of endothelial cells luminal and abluminal pits were effected in the same manner. Transport of macromolecules through coronary capillaries, over the short term studied, appears to be regulated by the ornithine decarboxylase/polyamine pathway.

N-methyl-D-aspartate receptor excitotoxicity involves activation of polyamine synthesis: protection by alpha-difluoromethylornithine.

We investigated the role of polyamines and their regulatory enzyme ornithine decarboxylase in N-methyl-D-aspartate-induced excitotoxicity in embryonic chick retina. N-Methyl-D-aspartate (200 microM) produced an early increase in ornithine decarboxylase activity, putrescine concentration, and Ca2+ entry, leading to selective neuronal death by 30 min. This response was attenuated by the ornithine decarboxylase inhibitor alpha-difluoromethylornithine and the N-methyl-D-aspartate receptor antagonist 5-aminophosphonovaleric acid. Exogenous putrescine increased intracellular putrescine and spermine levels and reversed neuroprotection by alpha-difluoromethylornithine, but not by 5-aminophosphonovaleric acid. N-Methyl-D-aspartate-receptor stimulation of putrescine/polyamine synthesis mediates abnormal Ca2+ entry and acute excitotoxic neuronal death. Postreceptor inhibition of the ornithine decarboxylase/polyamine cascade by alpha-difluoromethylornithine may provide neuroprotection against N-methyl-D-aspartate-induced excitotoxicity.

Capillary NMDA receptors regulate blood-brain barrier function and breakdown.

Polyamines and their regulatory synthetic enzyme ornithine decarboxylase (ODC) have been implicated in blood-brain barrier (BBB) breakdown following cryogenic injury. ODC activation and BBB breakdown are prevented by MK-801, indicating involvement of NMDA receptors. Studies in isolated rat cerebral capillaries supports the presence of NMDA receptors linked to ODC. NMDA (1-50 microM) stimulated capillary uptake of horseradish peroxidase, 2-deoxy-[14C]glucose, and 45 Ca in a receptor-, concentration-, polyamine- and Ca(2+)-dependent manner. We suggest that NMDA receptors may couple capillary transport of nutrients to glutamate-mediated neuronal excitation, and when overestimated disrupt normal BBB function.

Brain polyamines are controlled by N-methyl-D-aspartate receptors during ischemia and recirculation.

We studied the time course and molecular mechanisms of changes in brain polyamines and their rate-regulatory synthetic enzyme ornithine decarboxylase during reversible forebrain ischemia and recirculation in the gerbil. Bilateral carotid occlusion induced an acute (less than 2 minutes), transient increase in ornithine decarboxylase activity and putrescine level. After 15 minutes of ischemia, recirculation evoked an immediate (less than 1 minute) increase in ornithine decarboxylase activity and putrescine concentration that progressed over a 15-minute period. A small rise in spermidine and spermine also was observed. A secondary increase in ornithine decarboxylase activity and the levels of putrescine and spermidine commenced after 6 hours of recirculation. Pretreatment with a-difluoromethylornithine, a specific suicide inhibitor of ornithine decarboxylase, or MK-801, a noncompetitive N-methyl-D-aspartate receptor antagonist, abolished all early and delayed increases in ornithine decarboxylase activity and polyamine levels. This is the first demonstration that both ischemia and postischemic recirculation evoke rapid, transient increases in the activity of ornithine decarboxylase and the levels of polyamines, most notably the ornithine decarboxylase product, putrescine. Our results indicate that N-methyl-D-aspartate receptor activation (by an ischemically induced elevation of extracellular glutamate) is responsible for initiating the early and the delayed stimulation of ornithine decarboxylase activity. Ornithine decarboxylase activation causes the rapid rise in the levels of putrescine and higher polyamines observed in the acute response to ischemia and the acute and delayed response to postischemic recirculation. These polyamine changes may be involved in the pathophysiology of Ca2+ entry and neuronal death after brain ischemia.

Polyamines and Ca2+ mediate hyperosmolal opening of the blood-brain barrier: in vitro studies in isolated rat cerebral capillaries.

We recently presented evidence that the reversible opening of the blood-brain barrier (BBB) by the infusion of 1.6 M mannitol into the rat internal carotid artery is mediated by a rapid stimulation of ornithine decarboxylase (ODC) activity and putrescine synthesis in cerebral capillaries. We have now investigated this hypothesis further, using isolated rat cerebral capillaries as an in vitro model of the BBB. The ODC activity of cerebral capillary preparations was enriched up to 15-fold over that of the cerebral homogenate. Hyperosmolal mannitol in physiological buffer evoked a rapid (less than 15 s), concentration- and time-dependent increase in capillary ODC activity and an accumulation of putrescine and spermidine which was blocked by the specific ODC inhibitor, alpha-difluoromethylornithine (DFMO, 10 mM). Mannitol (1 M), as well as 2 M urea, evoked a two- to fivefold increase in the temperature-sensitive influx of 45Ca2+ and uptake of horseradish peroxidase (HRP) and 2-deoxy-D-[1-3H]glucose (DG), but not alpha-[1-14C]aminoisobutyrate, during a 2-min incubation. DFMO (10 mM) abolished 1 M mannitol-mediated stimulation of 45Ca2+ influx and uptake of HRP and DG, whereas 1 mM putrescine replenished capillary polyamines and reversed the DFMO effects. Mannitol (1 M)-induced stimulation of ODC activity and membrane transport processes was Ca2+-dependent and verapamil- and nisoldipine-sensitive. Phorbol myristate acetate (PMA, 10 nM), a protein kinase C activator, also evoked a two- to threefold stimulation of 45Ca2+ transport and HRP and DG uptake. This PMA effect was abolished by DFMO, suggesting involvement of rapid, ODC-controlled polyamine synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Polyamines mediate androgenic stimulation of calcium fluxes and membrane transport in rat heart myocytes.

The androgenic steroid hormone testosterone induced an early (less than 30-60 seconds) stimulation of endocytosis, hexose transport, and amino acid transport, monitored by the temperature-sensitive uptake of horseradish peroxidase, 2-deoxyglucose, and alpha-aminoisobutyrate, respectively, in rat ventricle cubes and acutely isolated ventricular myocytes. This stimulation was time- and concentration-dependent and was maximal at 10(-9) to 10(-8) M testosterone, consistent with androgen-receptor mediation. EGTA (2.5 mM), La3+ (1 mM), and verapamil (100 microM) ablated the hormonal response. The calcium ionophore A23187 (10 microM) induced an acute stimulation of endocytosis, amino acid transport, and hexose transport which was not further increased by testosterone (10(-8) M), suggesting a common effector pathway. Testosterone (10(-8) M) also evoked a rapid (less than 30 seconds) stimulation of 45Ca influx and efflux. Testosterone (10(-8) M) induced a rapid (less than 5 seconds) transient increase in ornithine decarboxylase (ODC) activity peaking (twofold to threefold) at 60 seconds, and an early (15 seconds) transient accumulation of polyamines peaking at 60 seconds in isolated myocytes. The specific, irreversible ODC inhibitor alpha-difluoromethylornithine (DFMO, 5-10 mM) blocked the testosterone-evoked increase in ODC activity and polyamine levels and the stimulation of Ca2+ fluxes, endocytosis, hexose transport, and amino acid transport. Putrescine (0.5-1 mM), the ODC product, reversed DFMO inhibition and restored the increase in polyamines, 45Ca fluxes, and Ca2+-dependent membrane transport processes. These results demonstrate that rapid, transient ODC-regulated polyamine synthesis is essential for androgenic stimulation of Ca2+ fluxes and membrane transport processes in ventricular myocytes. These findings support a model for signal transduction in which newly synthesized polyamines serve as intracellular messengers to regulate transmembrane Ca2+ movements, Ca2+-dependent membrane transport functions, and other Ca2+- and polyamine-sensitive processes in cardiac myocytes.

Polyamines mediate the reversible opening of the blood-brain barrier by the intracarotid infusion of hyperosmolal mannitol.

The blood-brain barrier (BBB) can be opened transiently by infusing a hyperosmolal solution of a non-electrolyte into the internal carotid artery. We investigated the hypothesis that capillary polyamines and their rate-regulating synthetic enzyme, ornithine decarboxylase (ODC), may be involved in mediating BBB breakdown in this model, as they are in BBB breakdown by focal cold injury. The intracarotid infusion of 1.6 M mannitol induced a prompt (less than 2 min) increase in ODC activity and the levels of polyamines in the ipsilateral hemisphere. Isolated cerebral capillary preparations and neural elements showed similar increases in ODC activity. The rank order of increase at 2 min, ODC (170%) greater than putrescine (90%) greater than spermidine (15%) greater than spermine (7%), was consistent with an activation of the ODC-regulated pathway of polyamine synthesis. The specific ODC inhibitor alpha-difluoromethylornithine (DFMO) blocked the 1.6 M mannitol-induced increase in ODC activity and the accumulation of polyamines, and concurrently prevented BBB breakdown, monitored by transport of intravenously administered Evans blue and alpha-[3H]aminoisobutyrate into cerebral tissue. Exogenous putrescine, the product of ODC activity, replenished brain polyamines and negated DFMO protection allowing BBB breakdown by 1.6 M mannitol. These experiments support the hypothesis that BBB breakdown induced by the intracarotid infusion of hyperosmolal mannitol is mediated by rapid, ODC-regulated synthesis of microvascular polyamines. In addition, increases in ODC-controlled polyamine synthesis in nerve cells may play a significant role in the pathophysiology of the reversible neuronal dysfunction, e.g. diazepam-sensitive seizure-like activity, enhanced glucose utilization, evoked by the intracarotid infusion of hyperosmolal mannitol.

Blood-brain barrier breakdown in cold-injured brain is linked to a biphasic stimulation of ornithine decarboxylase activity and polyamine synthesis: both are coordinately inhibited by verapamil, dexamethasone, and aspirin.

An early increase in ornithine decarboxylase (ODC) activity and polyamine levels in rat cerebral capillaries was previously implicated in the mediation of blood-brain barrier (BBB) breakdown in cold-injured brain. A time course study in rat cerebrum indicated that cold injury evokes a biphasic increase in ODC activity and polyamine levels in perilesional cortex. ODC activity rose sharply (fourfold) within 1 min, remained elevated for 5 min, and then returned to the basal level by 10 min. A transient rise in polyamine concentration followed in the rank order of putrescine greater than spermidine greater than spermine. A secondary rise in ODC activity commenced in perilesional tissue at 2-6 h and peaked (8.8-fold) at 48 h. Major increases in the content of putrescine (330%), spermidine (103%), and spermine (50%) developed at 48-72 h. alpha-Difluoromethylornithine (DFMO), a specific irreversible inhibitor of ODC, suppressed the evoked increase in ODC activity and abolished the associated increase in content of polyamines, findings indicating that the accumulation of polyamines in cryoinjured brain reflects enhanced synthesis resulting from an ODC-mediated increase in putrescine content. Cycloheximide and actinomycin D were without effect on the early increase in ODC activity but inhibited the delayed increase in ODC activity, an observation suggesting that the initial increase in activity reflects an activation of a cryptic ODC via a posttranslational process, whereas the delayed increase in activity results from ODC synthesis mainly under transcriptional control.(ABSTRACT TRUNCATED AT 250 WORDS)

Polyamines are intracellular messengers in the beta-adrenergic regulation of Ca2+ fluxes, [Ca2+]i and membrane transport in rat heart myocytes.

The beta-adrenergic agonist 1-isoproterenol (0.1 microM) evokes an acute (less than 5-10 sec) transient increase in the activity of ornithine decarboxylase (ODC), and the levels of polyamines (putrescine, spermidine, spermine) in acutely isolated rat ventricular myocytes. Isoproterenol rapidly (less than 15 sec) increases 45Ca influx and efflux, decreases [Ca2+]i, and stimulates Ca2+-dependent membrane transport (endocytosis, hexose transport, amino acid transport). The beta-adrenergic antagonist propranolol blocks isoproterenol-induced membrane transport. The ODC inhibitor alpha-difluoromethylornithine (DFMO, 5-10 mM) blocks the isoproterenol-evoked increase in ODC activity and polyamine levels and the changes in 45Ca fluxes, [Ca2+]i and membrane transport. Putrescine (0.5-1 mM) replenishes cellular polyamines and reverses the DFMO effect. These data exclude an increase in [Ca2+]i in stimulus-transport coupling, and support the hypothesis that polyamines are messengers in beta-adrenoceptor-mediated regulation of transmembrane Ca2+ fluxes, [Ca2+]i, and Ca2+-dependent membrane transport.

Polyamines mediate uncontrolled calcium entry and cell damage in rat heart in the calcium paradox.

Brief perfusion of heart with calcium-free medium renders myocardial cells calcium-sensitive so that readmission of calcium results in uncontrolled Ca2+ entry and acute massive cell injury (calcium paradox). We investigated the hypothesis that polyamines may be involved in the mediation of abnormal Ca2+ influx and cell damage in the calcium paradox. The isolated perfused rat heart was used for these studies. Calcium-free perfusion promptly (less than 5 min) decreased the levels of polyamines and the activity of their rate-regulating synthetic enzyme, ornithine decarboxylase (ODC), and calcium reperfusion abruptly (less than 15-180 s) increased these components. alpha-Difluoromethylornithine (DFMO), a specific suicide inhibitor of ODC, suppressed the calcium reperfusion-induced increase in polyamines and the concomitant increase in myocardial cellular 45Ca influx, loss of contractility, release of cytosolic enzymes, myoglobin, and protein, and structural lesions. Putrescine, the product of ODC activity, nullified DFMO inhibition and restored the calcium reperfusion-induced increment in polyamines and the full expression of the calcium paradox. Putrescine itself enhanced the reperfusion-evoked release of myoglobin and protein in the absence of DFMO. Hypothermia blocked the changes in heart ODC and polyamines induced by calcium-free perfusion and calcium reperfusion and prevented the calcium paradox. These results indicate that rapid Ca2+-directed changes in ODC activity and polyamine levels are essential for triggering excessive transsarcolemmal transport of Ca2+ and explosive myocardial cell injury in the calcium paradox.

Blood-brain barrier breakdown by cold injury. Polyamine signals mediate acute stimulation of endocytosis, vesicular transport, and microvillus formation in rat cerebral capillaries.

Polyamines have been previously implicated in the mediation of blood-brain barrier breakdown induced by cryogenic injury (H Koenig, AD Goldstone, CY Lu, Biochem Biophys Res Commun 116:1039, 1983). We studied acute (less than 5 minute) changes in capillary ultrastructure, microvascular permeability, and the levels of polyamines and their rate regulating synthetic enzyme ornithine decarboxylase (ODC) in rat cerebral cortex after focal cold injury. Microvascular permeability was measured by relative transport of intravenously administered fluorescein. Capillary ultrastructure was studied by quantitative stereology and morphometry after intravenous administration of horseradish peroxidase. Focal cold injury induced a 2.5-, 3.8-, 1.7-, and 1.4-fold increase in the levels of ODC, putrescine, spermidine and spermine, and a 46-fold increase in fluorescein uptake in perilesional cortex. Few capillaries in control cortex contained endocytic pits or horseradish peroxidase-positive vesicles, whereas most capillaries near lesions showed these structures. Cryoinjury induced a 5-fold increase in the relative volume of microvilli and horseradish peroxidase vesicles, a 2.3-fold increase in area of luminal endocytic pits, and a 6.3-fold increase in area of abluminal exocytic pits. The ODC inhibitor alpha-difluoromethylornithine blocked the cryoinjury-induced changes in ODC, polyamines, fluorescein uptake, and capillary ultrastructure. Putrescine negated the effect of alpha-difluoromethylornithine or capillary ultrastructure, and was previously shown to nullify the alpha-difluoromethylornithine effects on polyamines and fluorescein permeability (cited above). These data link rapid changes in ODC and polyamines to blood-brain barrier breakdown, and suggest that the abnormal permeability is associated with an acute, polyamine-mediated stimulation of microvillus formation, endocytosis, and vesicular transport in capillary endothelium.

Association of increased polyamine levels with isoproterenol-stimulated mucin secretion in the rat submandibular gland.

Incubation of rat submandibular gland slices with 50 microM isoproterenol for 10-40 min stimulated mucin secretion and induced a 3- to 4-fold increase in tissue concentrations of the polyamines putrescine, spermidine and spermine. alpha-Difluoromethylornithine, a specific inhibitor of ornithine decarboxylase, suppressed the isoproterenol-induced increase in submandibular polyamines and inhibited mucin secretion. Exogenous putrescine restored tissue polyamine levels and partially reversed the inhibitory effect of alpha-difluoromethylornithine on mucin secretion. Rapid increases in polyamine levels appear to mediate isoproterenol-stimulated mucin secretion in the rat submandibular gland.

Beta-adrenergic stimulation of Ca2+ fluxes, endocytosis, hexose transport, and amino acid transport in mouse kidney cortex is mediated by polyamine synthesis.

We recently found that the beta-adrenergic agonist 1-isoproterenol evokes a rapid (less than 5 min) Ca2+- and receptor-dependent stimulation of endocytosis, hexose transport, and amino acid transport in mouse renal cortex involving proximal tubule cells. This response is associated with increased Ca2+ fluxes and a mobilization of mitochondrial calcium, suggesting that stimulus-response (stimulus-"transport") coupling is mediated by cytosolic Ca2+. We show here that 1 microM isoproterenol evokes a rapid (less than 60 sec) transient increase in the activity of ornithine decarboxylase followed by an early (less than 2 min) sustained increase in putrescine, spermidine, and spermine concentrations in mouse kidney cortex slices in vitro. Small doses of isoproterenol (down to 24 nmol/kg) elicited a rapid (less than 2 min) increase in polyamines in vivo. The ornithine decarboxylase inhibitor alpha-difluoromethylornithine (5 mM) suppressed the testosterone-induced increase in polyamine levels and rates of endocytosis, hexose transport, and amino acid transport, measured by horseradish peroxidase, [14C]aminoisobutyric acid, and deoxy[3H]glucose uptake. alpha-Difluoromethylornithine also blocked the isoproterenol-induced increase in 45Ca influx and efflux and 45Ca redistribution; 0.5 mM putrescine nullified alpha-difluoromethylornithine inhibition and restored the increment in polyamines, 45Ca fluxes, endocytosis, hexose transport, and amino acid transport. These data implicate polyamine synthesis in isoproterenol stimulation of Ca2+ fluxes and membrane transport processes and support a model for signal transduction and stimulus-response coupling in which ornithine decarboxylase activation and polyamine synthesis play a pivotal role in regulating Ca2+ fluxes. In this model the polyamines generate local Ca2+ signals by stimulating Ca2+ influx or mobilizing intracellular calcium (or both) through a cation exchange reaction.

Blood brain barrier breakdown in brain edema following cold injury is mediated by microvascular polyamines.

A focal freeze injury to rat cerebral cortex induces an early (less than 5 min) increase in brain ornithine decarboxylase activity and an accumulation of polyamines involving cerebral microvessels. This polyamine synthesis correlates with the abnormal increase in microvascular permeability, monitored by uptake of Evans Blue and sod. fluorescein. The ornithine decarboxylase inhibitor alpha-difluoromethylornithine suppressed the injury-induced increment in spermidine and spermine and microvascular permeability. Putrescine nullified alpha-difluoromethylornithine inhibition and restored microvessel spermidine and spermine and the pathological increase in microvascular permeability. These results indicate that polyamine synthesis is obligatory for blood-brain barrier breakdown. alpha-Difluoromethylornithine may be useful in the treatment of vasogenic brain edema.

Beta-adrenergic stimulation evokes a rapid, Ca2+-dependent stimulation of endocytosis, hexose and amino acid transport associated with increased Ca2+ fluxes in mouse kidney cortex.

The beta-adrenergic agonist 1-isoproterenol evokes an acute (less than 5 min) stimulation of endocytosis, hexose transport and amino acid transport, measured by the temperature-sensitive uptake of HRP, 3H-DG and 14C-AIB, in mouse kidney cortex slices. This stimulation is concentration dependent and is maximal at 10(-8)-10(-7) M isoproterenol. Peroxidase cytochemistry showed that the hormonal increase in HRP uptake is confined to proximal tubules. The rapid membrane response is abolished in a calcium-free medium and by the beta-adrenergic antagonist propranolol, indicating Ca2+- and beta-adrenoreceptor-dependence. Isoproterenol (1 microM) rapidly (less than 30 sec) stimulates the influx and efflux of 45Ca in cortex slices. Isoproterenol also decreased mitochondrial 45Ca and increased soluble 45Ca. These results indicate that beta-adrenergic stimulation of membrane transport functions involves an increased influx of extracellular calcium and a mobilization of intracellular (mitochondrial) calcium. An increase in cytosolic Ca2+ concentration appears to be the regulatory signal for these membrane transport processes.

Androgenic stimulation of endocytosis, amino acid and hexose transport in mouse kidney cortex involves increased calcium fluxes.

Testosterone was previously shown to induce an early (less than 1 min) receptor-dependent stimulation of endocytosis, hexose and amino acid transport in mouse kidney cortex (Koenig, H., Goldstone, A. and Lu, C.Y. (1982) Biochem. Biophys. Res. Commun. 104, 165-172). Testosterone (10(-8) M) has now been found to stimulate rapidly (less than 30 s) the influx and efflux of 45Ca2+ in cortex slices. Testosterone also decreased mitochondrial 45Ca and augmented soluble 45Ca, indicating a mobilization of intracellular calcium. Incubation of cortex slices in calcium-free medium without or with 2.5 mM EGTA decreased basal endocytosis, hexose and amino acid transport and blocked the hormonal response. 100 microM verapamil blocked the hormonal response without affecting basal transport. The calcium ionophore A23187 rapidly stimulated endocytosis, hexose and amino acid transport. These data indicate that androgenic stimulation of membrane transport functions involves an increased influx of extracellular calcium and a mobilization of intracellular calcium. Increased cytosolic Ca2+ is probably the regulatory signal for these transport processes.

Glucocorticoids and aspirin inhibit and cyproterone acetate enhances the androgenic response in mouse kidney.

Glucocorticoids and aspirin antagonize the androgenic response in mouse kidney, but not in ventral prostate or seminal vesicles. These agents impeded the testosterone-mediated increase in kidney weight, cytochrome c oxidase, and lysosomal hydrolases and urinary excretion of lysosomal hydrolases and proteins. They also attenuated the testosterone-induced decrease in enzyme latency and membrane stability of kidney lysosomes. In contrast, the antiandrogen cyproterone acetate is weakly androgenic in kidney and potentiates testosterone-induced lysosomal enzymuria and proteinuria (synandrogenic effect).

Androgens regulate cell growth, lysosomal hydrolases and mitochondrial cytochrome c oxidase in mouse aorta.

The aorta in male mice shows higher activities of several lysosomal hydrolases and of cytochrome c oxidase, an inner mitochondrial membrane enzyme, than in female mice. Orchiectomy abolishes this sex difference, whereas testosterone administration induces an accretion of RNA and protein and elevated activities of lysosomal hydrolases and cytochrome c oxidase. However, the outer mitochondrial membrane enzyme monoamine oxidase is unaffected by sex, orchiectomy or testosterone. Thus, androgens regulate cell growth and enzymes associated with lysosomes and the inner mitochondrial membrane.