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Biomedical subjects

K Poulsen

Publications and source records attributed to K Poulsen.

At least 127 records · Page 7Linked to original sources
PubMed1983

Aggression-provoked huge release of submaxillary mouse renin to saliva.

In a normal male mouse, which had been kept isolated for some time, confrontation with another male mouse, resulted in aggressive behaviour, including fighting. The aggressive behaviour resulted in secretion of a few microlitre of saliva with vast renin concentration. The renin concentration in saliva reached values of 6000 Goldblatt units X ml-1, corresponding to 15 mg/ml of renin. This concentration is 6 orders of magnitude higher than normal plasma renin concentrations. The secretory pattern could be mimicked by ip injection of pharmacological doses (2-18 mg/kg) of the alpha-adrenergic agonist phenylephrine. This is probably the first demonstration of a physiological secretion of renin to saliva which may be of importance since renin most likely is injected into the opponent or prey through bites.

Aggression↗
PubMed1983

The biochemistry of aggression-provoked renin.

The biochemistry of the renin-angiotensin system in aggressive mice may question a simple role of the system in blood pressure regulation. When male mice are fighting, their plasma concentration of active renin may rise several hundred fold without affecting blood pressure. The source of this renin is secretion to the blood from the submaxillary gland and the kidneys, but also small salivary glands may contribute. A further source may be salivary renin transferred by bites from one animal to another, as indicated by recent experiments. The renin concentration in saliva of an aggressor during a fight reaches values of 6000 GU/ml (15 mg/ml). The huge increase in plasma renin is caused by fully enzymatic active 40 000 Mw renin. Preliminary data, collected in order to study whether this renin is active also in vivo, show the following: Inactive renin is present in a small invariable concentration. The renin substrate is consumed in vivo and the measured generation rate of angiotensin is that expected from the renin and substrate concentration. The data seem to indicate that the high concentration of aggression-provoked renin is active in vivo. It is unknown how the mouse protects its blood pressure against this hyperactive pressor system.

Aggression↗
PubMed1983

Renin precursors.

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Amino Acid Sequence↗
PubMed1982

Vascular and tubular renin in the kidneys of mice.

Monospecific antisera and the immunocytochemical PAP-method have been used to localize renin in the kidneys of mice. With this procedure, reaction product was not only observed in the epitheloid cells of kidney vessels but also in kidney tubules: in the apical portion of proximal tubule cells and in some cells of the connecting and the cortical collecting tubule. To answer the question, whether the occurrence of renin in kidney tubule cells is the consequence of tubular synthesis or that of glomerular filtration of plasma renin followed by its uptake from the tubular lumen, tracer experiments with radioiodinated renin and with horseradish peroxidase were undertaken. The results of these studies as well as other arguments suggest reabsorptive pinocytosis of the filtered hormone as the source of tubular renin.

Animals↗
PubMed1982

Inhibition of mouse fibroblast interferon by gangliosides. Differential effects on biological activity and on induction of (2'--5')oligoadenylate synthetase.

Gangliosides are potent inhibitors of the antiviral activity of mouse fibroblasts and other beta-interferons. We have compared the effects of gangliosides on antiviral and antigrowth activities of mouse fibroblast interferon and on the induction of (2'--5')oligoadenylate synthetase, one of the enzymes implicated in the antiviral state induced by interferon. Whereas both biological effects appear to be inhibited by gangliosides in an analogous fashion, inhibition of induction of (2'--5')oligoadenylate synthetase does not correlate with inhibition of vesicular stomatitis virus replication. Ganglioside concentrations that inhibit the interferon-induced (2'--5')oligoadenylate synthetase to levels close to those of uninduced cells, still allow for a 100--1000-fold reduction of viral yield. Significantly higher ganglioside concentrations are required to prevent completely the antiviral effect. This biphasic relationship between (2'--5')oligoadenylate synthetase levels and inhibition of viral yield suggests that no or very small increases in synthetase levels are involved in inhibition of virus by between two and three orders of magnitude.

2',5'-Oligoadenylate Synthetase↗
PubMed1982

Inhibition of rat renin by antibody elicited against pure mouse renin and the effect on blood pressure.

Antibodies raised against mouse submaxillary renin showed affinity for rat renal renin. The affinity was characterized by enzyme kinetics in vitro. The antibodies and the purified Fab fragments showed total inhibition of rat renin, with a Ki of 6.5 +/- 0.7 x 10(-8)mol/l for the Fab fragments. The effect of enzymatic inhibition on blood pressure in anaesthetized rats was compared with converting enzyme inhibition. The antibodies showed a significant effect on blood pressure, with a depressor effect corresponding to that of the converting enzyme inhibitor [SQ 20 881]. The reduction of mean arterial pressure was from 116 +/- 3 to 108 +/- 3 mmHg for the antibodies and to 107 +/- 4 mmHg for the converting enzyme inhibitor. The pressor response of infused rat renal renin was totally blocked by the antibodies while pressor responses of angiotensin II were unchanged.

Angiotensin II↗
PubMed1982

Vast release of submaxillary mouse renin to saliva after stimulation with cholinergic, beta-adrenergic but especially alpha-adrenergic agonists.

alpha-adrenergic stimulation with phenylephrine causes release of vast amounts of mouse submaxillary gland renin to saliva. The amount released is about 100-fold higher than that released after beta-adrenergic stimulation with isoproterenol and about 1000-fold higher than the amount released after cholinergic stimulation with pilocarpine. alpha-blockade with phenoxybenzamine before phenylephrine stimulation strongly inhibits the renin release. However, phenoxybenzamine or beta-blockade with propranolol before isoproterenol stimulation have no effect on the amount of renin released. Thus, the release of submaxillary mouse renin to saliva is triggered mainly by activation of alpha-adrenergic receptors. Renin in cholinergic and alpha- and beta-adrenergic stimulated saliva has the same molecular weight and the same specific enzymatic activity as renin in the submaxillary gland. This indicates that renin is secreted to saliva, and probably also to the blood, in its fully enzymically active 40000 mol.wt. form regardless of the stimulus used. The vast amounts of renin released to saliva (up to 600 Goldblatt Units) demonstrate that submaxillary mouse renin is secreted predominantly to saliva and much less to the blood. The mouse submaxillary gland therefore seems to have an exocrine rather than an endocrine role for release of renin.

Adrenergic alpha-Agonists↗
PubMed1982

In vitro studies on the conversion of the biosynthetic precursor of renin.

The initial translation product of mouse submaxillary gland mRNA has a molecular weight of about 50,000. We have now translated renin mRNA in frog oocytes which are known to be able to remove the so-called "pre"- or "signal"- sequence from products of injected mRNAs. From these injected oocytes, we could precipitate with antirenin a 48,000 dalton polypeptide. Treatment with kallikrein or trypsin of the oocyte product resulted in a decrease in amount of this 48,000 dalton protein and a corresponding increase in a 45,000 dalton protein, precipitable with antirenin. We conclude that the initial translation product of renin mRNA is a preprorenin of molecular weight 50,000, which in oocytes is enzymatically cleaved to render 48,000 dalton prorenin. Although kallikrein may be a physiological activator of renin, it appears to be not the only one since no mature, 40,000 dalton renin was formed.

Animals↗
PubMed1981

In vivo activity of purified mouse brain renin.

Mouse brain renin and kidney renin were purified by a 3-step procedure: acetone powder extraction. Sephadex G-100 chromatography, and blue agarose affinity chromatography. The latter efficiently separated from cathepsin D-like acid protease activity. Mouse brain renin had an optimum of enzyme activity of pH 7.0. This differed from mouse kidney renin, which had an optimum at pH 8.5. In vitro, brain renin formed angiotensin I from rat plasma angiotensinogen and had no angiotensinase activity. Mouse brain renin was inhibited by monospecific antibodies raised against pure mouse submandibular gland renin. In vivo activity of the enzyme was tested by injection of brain renin into the lateral brain ventricle of rats. This resulted in the formation of angiotensin I from endogenous brain angiotensinogen, in the stimulation of water uptake, and in a long-lasting increase of arterial blood pressure. The latter could be blocked by the competitive angiotensin II receptor antagonist, saralasin. The results showed that brain renin is active under physiological conditions.

Angiotensin II↗
PubMed1981

High levels of active 40 000-dalton renin in mouse saliva, but no evidence of inactive or high molecular weight forms.

The presence of renin in parasympathetically elicited mouse saliva was demonstrated by using both the antibody trapping method, which measures renin's enzymatic activity, and a direct radioimmunoassay, which detects the renin molecule by its antigenic properties. Crossed immunoelectrophoresis of saliva samples using an antiserum elicited against pure submaxillary renin showed only one precipitation line, indicating the presence of only one form of renin. The position of the line was similar to that found when submaxillary gland extract was subjected to crossed immunoelectrophoresis. Tandem crossed immunoelectrophoresis showed complete identity between antigenic determinants in submaxillary and salivary renin. An apparent molecular weight of about 35 000 and 38 000 was found when saliva samples were subjected to gel filtration on Ultrogel AcA 44 and Sephadex G-100, respectively. No high molecular weight forms were present and no inactive forms could be demonstrated after limited pepsin or trypsin proteolysis. The specific enzymatic activity of renin in pilocarpine saliva was 0.37 Goldblatt Units (G.U.) . microgram-1, which is identical to that of pure submaxillary gland renin (0.41 G.U. . microgram-1) and to that to the storage form of renin in the submaxillary gland (0.4 G.U. . microgram-1) An identical Km value was found for salivary renin, 1.01 microM, and for pure submaxillary renin, 0.98 microM. It is concluded that renin in pilocarpine-elicited saliva is similar to the storage form of renin in the submaxillary gland with respect to molecular weight, enzymatic and immunological properties.

Animals↗
PubMed1981

Renin immunocytochemistry of the differentiating juxtaglomerular apparatus.

The differentiation of the juxtaglomerular apparatus in fetuses and newborn mice was investigated by renin immunocytochemistry and electron microscopy. Three to four days before delivery and prior to other organs renin was found in the fetal kidney. At this early time immunoreactivity was preferentially located in cells of the media of interlobular arteries. In newborn mice the formation of new nephrons and maturation of their glomeruli was accompanied by a shift in renin localization from the interlobular arteries to the afferent arterioles. At the same time, kidney renin content and concentration increased rapidly. Synchronously with renin immunoreactivity, during the capillary loop stage of glomerular development, granulated epitheloid cells became visible in the afferent arteriole.

Animals↗
PubMed1981

Renin in the mouse kidney has a molecular weight of 40 000.

1. Mouse kidney was homogenized in a mixture of serine-metallo- and thiol-enzyme inhibitors. The homogenate proteins were separated with respect to size and charge by gel filtration, agarose electrophoresis and polyacrylamide-gel electrophoresis. 2. Renin was localized by its enzymatic activity by using the antibody trapping radio-immunoassay for angiotensin I, before and after acid treatment and limited proteolysis. Renin was also localized by its antigenic properties by using antirenin antibodies elicited against pure mouse submaxillary renin. The antibody cross-reacted fully with mouse kidney renin and with high-molecular-weight renin forms in mouse plasma. 3. In the kidney only fully enzymically active 40 000 renin could be detected enzymically and antigenically. No high-molecular-weight renin or inactive renin was demonstrable. 4. Two electrophoretically different renin forms were seen in accordance with renin being a glycoprotein. They were both fully enzymically active with identical specific enzymatic activities. 5. The mouse kidney renin had a specific enzymatic activity identical with that of pure mouse submaxillary renin, being 0.4 Goldblatt unit/microgram.

Animals↗
PubMed1981

Characterization of aggression-provoked renin from an unknown source in male mice.

1. In male mice without kidneys and submaxillary, as well as sublingual, glands aggressive behaviour causes a vast release of renin [J. Bing & K. Poulsen (1979) Acta Physiologica Scandinavica, 107, 251-256]. 2. This resulted in about an 800-fold increase in plasma renin concentration from the control level of 0.52 (range 0.15-0.8) Goldblatt unit (G.U.) x 10(-3)/ml to 430 (range 300-500) G.U. x 10(-3)/ml after aggression. 3. The aggression-provoked renin fulfil all the criteria so far studied for being active renin, identical with normal mouse plasma renin and pure submaxillary mouse renin. 4. It generates angiotensin I with renin substrate and Km (1.2 mumol/l) is the same. It is neutralized by pepstatin but not by inhibitors of metallo-, thiol and serine proteinases, indicating that it is an aspartate proteinase (acidic proteinase). 5. It is a 40 000-mol.wt. renin, which has full enzymatic activity with a specific enzymatic activity of 0.32 G.U./micrograms, identical with that of normal plasma renin. 6. Its enzymatic activity is neutralized by a specific antibody against pure submaxillary renin. It is measureable in the direct renin radioimmunoassay with a dilution curve which parallels that of the standards. It demonstrates complete antigenic identity with pure submaxillary renin in crossed immunoelectrophoresis. 7. Its origin is unknown.

Aggression↗
PubMed1981

Aggression-provoked renin release from an unknown source in male mice.

1. An 800-fold increase in plasma renin occurs after aggressive behaviour in male mice without kidneys and submaxillary glands. 2. The aggression-provoked renin fulfils all the criteria so far studied for being identical with renin. 3. It is an acid proteinase which generates angiotensin I with the same Km and specific enzymatic activity as pure submaxillary renin and normal plasma renin. 4. It is immunologically identical with submaxillary renin in the direct renin assay and in crossed immunoelectrophoresis. 5. It is present in plasma as fully enzymatically active 40 000-mol. wt. renin. 6. It is not likely that it arises from an inactive precursor or binding protein in plasma, since there is no inactive renin present and the high-molecular-weight forms of renin are also present after the fighting. 7. None of many organs so far studied can account for the release. 8. Synthesis of renin de novo during fighting is not likely since it is released also after blockade in vivo of protein synthesis. 9. Origin of the renin is unknown.

Aggression↗