Stimulation of endothelial angiotensin-converting enzyme by morphine via non-opioid receptor mediated processes.

In this study, we examined the influence of morphine and naloxone on the enzymatic activity of different ecto-peptidases located on the surface of endothelial cells. Morphine increased in a concentration dependent manner the degradation of Leu-enkephalin in cultivated bovine aortic endothelial cells. Naloxone, a morphine antagonist, did not prevent this effect, but caused it as well.

Effect of ethanol drinking on the gene expression of opioid receptors, enkephalinase, and angiotensin-converting enzyme in two inbred mice strains.

There is convincing evidence that genetic factors contribute to the predisposition to alcoholism. In this respect, alcohol-preferring (like C57BL/6 mice) and alcohol-avoiding lines (like DBA/2 mice) of animals served as models in the search for neurobiological substrates of excessive ethanol consumption. One of the systems that is thought to be associated with the incidence of alcoholism is the endogenous opioid system.

Gene expression and activity of specific opioid-degrading enzymes in different brain regions of the AA and ANA lines of rats.

There is increasing evidence that alcoholism runs in families suggesting that genetic factors may play a role. In support of this hypothesis, the alcohol-preferring (AA) and the alcohol-avoiding (ANA) rat lines have been developed through selective outbreeding. Numerous studies indicate that the endogenous opioid system may be involved in controlling ethanol consumption.

Screening of selected basidiomycetes for inhibitory activity on neutral endopeptidase (NEP) and angiotensin-converting enzyme (ACE).

Aqueous extracts of 27 basidiomycetes were investigated for their ability to inhibit the activity of angiotensin-converting enzyme (ACE) and neutral endopeptidase (NEP). The extracts of 5 fungi inhibited both, ACE and NEP activity, another 18 extracts showed inhibition of the NEP activity whereas only 1 basidiomycete inhibited the ACE activity exclusively. The IC50 values for the ACE inhibition are rather high (between 200 and 1500 micrograms/ml) in comparison to the IC50 of the NEP inhibition (between 40 and 2000 micrograms/ml).

Dexamethasone induced enhanced enkephalin degradation by angiotensin-converting enzyme (ACE) of endothelial cells.

The Leu-enkephalin breakdown by ectopeptidases of cultivated endothelial cells is increased in a concentration-dependent manner by dexamethasone treatment. This glucocorticoid induced selectively the angiotensin-converting enzyme (ACE) of the cells. The activity of the closely related enzyme neutral metalloenopeptidase (NEP) and the aminopeptidase N (APN) also present on the endothelial cell surface were not affected or slightly decreased by dexamethasone.

The enzymatic degradation of bradykinin in semen of various species.

The degradation of bradykinin in semen and on washed sperm cells of various species (human, pig, cattle, sheep) is mainly controlled by two peptidases, the angiotensin-converting enzyme (ACE/kininase II; E.C. 3.

Degradation of bradykinin in semen of ram and boar.

The pattern of bradykinin (BK; Arg1-Pro2-Pro3-Gly4-Phe5-Ser6-Pro7-Phe8-Arg9)-inact iva ting peptidases in semen of boar and ram was investigated. The degradation of BK in semen was completely abolished by the metalloprotease inhibitors EDTA and o-phenanthroline. Inhibitors of angiotensin-converting enzyme (ACE; EC 3.

Reduced degradation of biological active peptides during in vitro aging of endothelial cells.

Endothelial cells under in vitro cultivation show an age-dependent decrease in peptide-cleavage activity. After a number of passages, the rates of Leu-enkephalin and bradykinin decomposition by cultivated cells were diminished as compared to their counterparts before in vitro aging. In addition, these cells have been found to be less capable of converting angiotensin I into angiotensin II.

[Tyrosine splitting aminopeptidases on cultivated anterior hypophyseal and vascular endothelial cells].

Activities of aminopeptidases for a tyrosine peptide hydrolysis were characterized with Tyrosyl-7-amino-4-methyl-coumarin as substrate on in vitro cultivated anterior pituitary cells, respectively, on aortic endothelial cells. Furthermore the corresponding activities were measured in different fractions of the cells. The activities of the enzymes in soluble fractions of the cell homogenates are comparable with aminopeptidases of cytosolic compartments of other tissue samples.

Investigations on the influence of bradykinin upon the motility of ram spermatozoa.

The influence of bradykinin, a component of the kallikrein-kinin system, on the motility of ram spermatozoa was examined in vitro (photometric motility evaluation, penetration test in cervical mucus of sheep, estimation of the percentage of forward-moving spermatozoa in the thermal resistance test). Whereas the motility was found to be influenced by bradykinin the acrosomal status remained undisturbed by it. With fresh as well as with frozen semen, the drug mainly increased the motility of samples with a low initial motility.

Angiotensin-converting enzyme and other peptidolytic enzymes in human semen and relations to its spermatologic parameters.

Angiotensin-converting enzyme (ACE) and other enzymes of the renin-angiotensin system (RAS) occur in human semen in high activities. In contrast to bull ejaculates, not all zinc-dependent metallopeptidases are found to be in close correlation to the microscopically determined semen parameters; such a relationship was established only partly for the ACE. On the other hand, the RAS-dependent spermatozoa-bound enzymes, inclusive ACE, uniformly show negative correlations to the spermatologic parameters of human semen.

Occurrence and potential importance of angiotensin-converting enzyme in semen of boars.

The activities of angiotensin-converting enzyme (ACE) and leucinaminopeptidase (LAP) are positively correlated with corresponding concentrations of sperm cells in semen of boars kept under normal conditions. The spermatozoa bound ACE activity, in general, does not reflect differences in the quality of semen (bull and boars). On the other hand, the ACE activity directly bound on the sperm cells is significantly elevated, if 'exogenic noxes' (by feeding or keeping) influence the fertility of boars in a drastic manner.

Occurrence and potential importance of selected peptidases in bull ejaculates.

The zinc containing peptidases angiotensin-converting enzyme (ACE), neutral metalloendopeptidase (NEP), and leucine aminopeptidase (LAP) occur in bull ejaculates in high activities. These enzyme activities are in close correlation with some routineously determined semen parameters. These ejaculat parameters are used for quality classification and selection of ejaculates and are according to long term experience in good correlation to the male fertility.

[Possible involvement of the renin-angiotensin system in reproduction. III. Occurrence and role in pregnancy].

To clarify a possible participation of the renin-angiotensin-system (RAS) in physiological processes of pregnancy, findings are listed about occurrence and variations of RAS components in uterus, placenta, amniotic fluid, fetal membranes, fetus and serum. There exist complete and independent RAS in the respective organs and tissues. During pregnancy concentrations and/or activities of the components change, but in different ways and non-uniforming.

[Possible involvement of the renin-angiotensin system in reproduction. II. Occurrence and role in the female reproductive tract].

Biochemical and immunological studies of the last years reveal the existence of an "ovarian renin-angiotensin system (RAS)". Despite of the low angiotensin-conterting enzyme (ACE) activity in the ovary the follicular fluid is rich in angiotensin II (AII). The detection of AII receptors on cells within maturating follicles proves them as AII targets.

[Possible involvement of the renin-angiotensin system in reproduction. I. Occurrence and role in the male reproductive tract].

With regard to the blood pressure the regulative function of the renin-angiotensin-system (RAS) is well known. Knowledge of the last years is that components of the RAS are available also in organs and excrets of the male reproductive tract. So, the angiotensin-converting-enzyme (ACE) - a key enzyme of the RAS - exists in the testes in an extraordinary high activity exceeding those of the lung tissue.

[The determination of neutral metalloendopeptidase (enkephalinase A) in biological material].

The simple determination of the Neutral Metalloendopeptidase (NEP, Enkephalinase A) with the known fluorogenic substrate Dansyl-D-Ala-Gly-(pNO2)Phe-Gly is disturbed by high concentrations of the Angiotensin-Converting-Enzyme (ACE). ACE hydrolyzes this substrate too but to a smaller degree. In some tissues and body fluids a further substrate hydrolysis takes place by any indefinite proteases.

[Effect of a proliferation- stimulating preparation from bovine brain on cultured calf aortic endothelial cells].

A preparation from bovine brain (HS-3) stimulates the proliferation of a calf aortic cell line (BKEz-7) in concentrations between 50-200 micrograms/ml. It is especially effective at low inoculum cell density, it economizes fetal serum and is very efficient as additive for the improvement of inadequate sera. Important questions for the practical use as the properties of the preparation with regard to durability and sterile filtration have been investigated.

Influences of the chemical structure on the activity of new inhibitory compounds of the angiotensin-converting enzyme.

The ACE inhibitory activity of some perimidines, chinazolinones and amidinohydrazones is described. Relations were found between the chemical structure and the inhibitory activity on the ACE.