Distinct down-regulation of cardiac beta 1- and beta 2-adrenoceptors in different human heart diseases

Cardiac beta-adrenoceptor density and beta 1- and beta 2-subtype distribution were examined in human left ventricular myocardium from transplant donors serving as controls and from patients with mitral valve stenosis, aortic valve stenosis, idiopathic dilated cardiomyopathy, and ischaemic cardiomyopathy respectively. The total beta-adrenoceptor density was similar in transplant donors and patients with moderate heart failure (NYHA II-III) due to mitral valve stenosis, but was markedly reduced in all forms of severe heart failure (NYHA III-IV) studied. A reduction of both beta 1- and beta 2-adrenoceptors was found in patients with severe heart failure due to mitral valve stenosis or ischaemic cardiomyopathy. In contrast, a selective down-regulation of beta 1-adrenoceptors with unchanged beta 2-adrenoceptors and hence a relative increase in the latter was observed in idiopathic dilated cardiomyopathy and aortic valve stenosis. It is concluded that the extent of total beta-adrenoceptor down-regulation is related to the degree of heart failure. Selective loss of beta 1-adrenoceptors is not specific for idiopathic dilated cardiomyopathy but also occurs in aortic valve stenosis. Changes in beta 1- and beta 2-subtype distribution are rather related to the aetiology than to the clinical degree of heart failure.

Effects of carbachol and (-)-N6-phenylisopropyladenosine on myocardial inositol phosphate content and force of contraction

1. The effects of carbachol and the A1-adenosine receptor agonist (-)-N6-phenylisopropyladenosine (PIA) on force of contraction and inositol lipid metabolism were studied in electrically driven left auricles and papillary muscles isolated from guinea-pig hearts. Both carbachol and PIA (0.01-10 microM) had concentration-dependent negative inotropic effects in auricles. In papillary muscles PIA had no inotropic effect. Carbachol also had no inotropic effect at low concentrations (0.01-1 microM) but at 10-100 microM it exerted a slight positive inotropic effect. 2. In auricles and papillary muscles both carbachol and PIA concentration-dependently increased inositol trisphosphate (IP3; significant at 1 microM). Accordingly phosphatidylinositol bisphosphate (PIP2), the precursor of IP3, was reduced. All effects of carbachol and PIA were antagonized by atropine (10 microM) and 1,3-dipropyl-8-cyclopentylxanthine (DPCPX; 20 microM) respectively, indicating receptor-mediated effects. 3. In auricles the negative inotropic effects of carbachol and PIA preceded the increase in IP3. 4. In papillary muscles the increase in IP3 preceded the slight positive inotropic effect of carbachol, indicating that the M-cholinoceptor-mediated increase in IP3 and force of contraction may be related. However, PIA showed a comparable increase in IP3 but no inotropic effect, indicating a dissociation between those parameters. 5. In conclusion, in previous studies a close relation between increases in IP3 and force of contraction has been shown after alpha 1-adrenoceptor stimulation. The present study with carbachol supports this view. However, the present data for PIA could not show such a close relationship, questioning the role of IP3 as an endogenous regulator of force of contraction.

Role of erythropoietin in adaptation to hypoxia

The glycoprotein hormone erythropoietin (EPO) counteracts tissue hypoxia by increasing the systemic oxygen-carrying capacity. It induces augmentation of red blood cell mass by stimulating the formation and differentiation of erythroid precursor cells in the bone marrow. EPO production is increased under various forms of diminished oxygen supply such as anemic or hypoxic hypoxia. In the adult organism, the kidneys are the major source of EPO. The precise nature of the cells responsible for renal EPO production, however, has not yet been elucidated. Most likely, peritubular cortical cells, e.g. interstitial or endothelial cells, are involved in the elaboration of the hormone. From the observation that isolated perfused rat kidneys produce EPO in an oxygen-dependent fashion we conclude that the 'oxygen sensor' that controls hypoxia-induced EPO synthesis is located in the kidney itself. Within the kidneys, the local venous oxygen tension which reflects the ratio of oxygen supply to oxygen consumption is measured and transformed into a signal that regulates the formation of EPO. However, the mechanism by which a decrease of oxygen delivery to the kidneys is linked to an enhanced EPO gene expression is not yet known. Two possible mechanisms of regulation are discussed: First, renal hypoxia could lead to enhanced formation of metabolic mediators, for example prostaglandins or adenosine, which might stimulate EPO gene transcription by increasing cellular levels of second messenger molecules. Second, some kind of molecular 'oxygen receptor' such as a heme protein, that controls EPO formation by an oxygen-dependent conformational change, could mediate signal transduction.

[Fallot's tetralogy in a calf--a case report]

A report is given on a calf with tetralogy of Fallot. This is the most common cyanotic congenital heart lesion in calves. Diagnosis was made by two-dimensional echocardiography and heart catheterisation. Tetralogy of Fallot was confirmed by necropsy.

Expression of a functionally active cardiac fatty acid-binding protein in the yeast, Saccharomyces cerevisiae

The unicellular eukaryotic microorganism, Saccharomyces cerevisiae, transformed with a plasmid containing a cDNA fragment encoding bovine heart fatty acid-binding protein (H-FABP) under the control of the inducible yeast GAL10 promoter, expressed FABP during growth on galactose. The maximum level of immunoreactive FABP, identical in size to native protein as judged from SDS-polyacrylamide gel electrophoresis, was reached after approximately 16 hours of induction. Analysis of particulate and soluble subcellular fractions showed that FABP was exclusively associated with the cytosol. FABP expressed in yeast cells was functional as was demonstrated by its capacity to bind 14C-oleic acid in an in vitro assay. Growth of the transformants on galactose as the carbon source was significantly retarded at 37 degrees C. Whereas the fatty acid pattern of total lipids was not altered in transformed cells, desaturation of exogenously added 14C-palmitic acid was significantly reduced both at 30 and 37 degrees C. The lowest percentage of radioactively labeled unsaturated fatty acids was found in the phospholipid fraction.

[Boogenic human diseases]

Basing on observations from practice and clinic, a survey is given (in two tables) concerning the disturbances of human health due to the handling of cattle, and their causes.

Differential antagonism by 1,3-dipropylxanthine-8-cyclopentylxanthine and 9-chloro-2-(2-furanyl)-5,6-dihydro-1,2,4-triazolo(1,5-c)quinazolin-5-im ine of the effects of adenosine derivatives in the presence of isoprenaline on contractile response and cyclic AMP content in cardiomyocytes. Evidence for the coexistence of A1- and A2-adenosine receptors on cardiomyocytes

The antagonism by the A1-adenosine receptor antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX) and the A2-adenosine receptor antagonist [9-chloro-2-(2-furanyl)-5,6-dihydro-1,2,4-triazolo (1,5-c)quinazolin-5-imine] (CGS 15943A) of the effects of the A1-adenosine receptor agonist (-)-N6-phenylisopropyladenosine (R-PIA) and the A2-adenosine receptor agonist 5'-N-ethyl-carboxamideadenosine (NECA) in the presence of isoprenaline on contractile response and cyclic AMP (cAMP) content in cardiomyocytes from guinea pig cardiac ventricles were studied. In electrically driven (1 Hz) guinea pig ventricular cardiomyocytes R-PIA concentration-dependently (0.0001-100 microM) reduced the stimulatory effects of isoprenaline (0.01 microM) on contractile response and on cAMP content. The A1-adenosine receptor antagonist DPCPX (0.3 microM) antagonized the effects of R-PIA on contractile reponse and on cAMP content, whereas the A2-adenosine receptor antagonist CGS 15943A (0.01 microM) was ineffective. NECA (0.0001-100 microM) reduced the effects of isoprenaline (0.01 microM) on contractile response to about the same extent as R-PIA. However, NECA did not change cAMP content. DPCPX (0.3 microM) antagonized the effects of NECA on contractile response and evoked a cAMP-increasing effect of NECA, which was 38% of the isoprenaline value at most. In contrast, CGS 15943A did not affect the reduction of contractile response induced by NECA, whereas CGS 15943A revealed a cAMP-decreasing effect of NECA (0.1-10 microM). This study provides functional evidence that both, cAMP-decreasing A1- and cAMP-increasing A2-adenosine receptors are present on ventricular cardiomyocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

[Formaldehyde-fixed human varicose vein bioprosthesis with siliconized inner surface for hemodialysis. Clinical analysis of 165 transplants]

With the submitted study of 165 HVV-vessel-transplantations the marking properties like reduced immunogenity, primary athrombogenicity, form fixated vascular lumen, ability for punction, flow reduction and stability for storage were possible to prove. Few complications (thromboses, aneurysms, infections) and also low rate of revision marks the long-term progress of this bioprosthesis. It will be stated with emphasis, that the use of this vascular device is indicated, if the patient's veins for creation of an arteriovenous vascular access is not available. In long-term progress the rate of function is better in comparison with other similar or synthetic materials for prostheses.

Positive inotropic effect of carbachol and inositol phosphate levels in mammalian atria after pretreatment with pertussis toxin

The m-cholinoceptor agonist carbachol elicits a negative inotropic effect in mammalian atria. Pretreatment with pertussis toxin converts the negative to a positive inotropic effect. In this study we investigated the time course of the effects of carbachol on force of contraction and phosphoinositide products in electrically driven left auricles from guinea pig hearts after pretreatment with pertussis toxin (180 micrograms/kg i.v.; 24 hr). Inositol phosphates and phosphatidylinositols were labeled with [3H]inositol and separated with high-performance liquid chromatography and thin-layer chromatography, respectively. All experiments were performed in the presence of LiCl (10 mmol/l). The positive inotropic effect of carbachol (10 mumol/l) began within 2 min and was maximal within 15 min. Inositol 1,4,5-trisphosphate rose within 1 min followed by an increase in inositol 1,3,4,5-tetrakisphosphate, inositol 1,3,4-trisphosphate, inositol 1,4-bisphosphate and inositol 1-phosphate beginning within 2 min. It is concluded that the carbachol-induced positive inotropic effect is associated with an increase in the presumed second messengers inositol 1,4,5-trisphosphate and inositol 1,3,4,5-tetrakisphosphate. Since the increase in inositol 1,4,5-trisphosphate precedes the increase in force of contraction, it may initiate the positive inotropic effect. The increase in inositol 1,3,4,5-tetrakisphosphate may be involved in maintaining the positive inotropic effect of carbachol.

Role of protein kinase C in renal vasoconstriction caused by angiotensin II

In this study we have examined the subcellar pathways along which angiotensin II (ANG II) causes renal vasoconstriction. Using the isolated perfused rat kidney model, we found that renal vasoconstriction produced by ANG II (100 pM) was not altered by the calmodulin antagonists calmidazolium (1 microM) and N-(6-aminohexyl)-5-chloro-1-naphthalensulfonamide (W-7, 10 microM) but was blunted by staurosporine (100 nM) and 1-(5-isoquinolinylsulfonyl)-2-methyl-piperazine (H-7, 50 microM), two structurally distinct putative protein kinase C inhibitors. The phorbol ester 4 alpha-phorbol 12,13-didecanoate (1-100 nM) did not alter renal vascular resistance, whereas phorbol 12-myristate 13-acetate (PMA, 1-100 nM) caused potent and dose-dependent vasoconstriction that was prevented by staurosporine (100 nM) and H-7 (50 microM). The vasoconstrictory effects of ANG II and PMA were attenuated by the calcium channel blockers verapamil (5 microM) and nifedipine (5 microM) and were reversibly inhibited when cobaltous chloride (2 mM) was added to the perfusate. Taken together, our findings support the concept that the renal vasoconstrictory effect of ANG II is essentially mediated by protein kinase C activation, which either requires or enhances the entrance of extracellular calcium.

[Examination of cattle with respiratory diseases for Mycoplasma and bacterial bronchopneumonia agents]

A total of 247 mycoplasma strains was isolated from 435 lungs, tracheobronchial secretions and nasal swabs originating from cattle with symptoms of bronchopneumonia. Mycoplasma (M.) bovis was found 89 times (36%) and was the most common mycoplasma species in the lungs. M. bovirhinis, M. bovigenitalium, M. spec. and Acholeplasma (A.) laidlawii were isolated 158 times (64%). Among these mycoplasmas M. bovirhinis was the most widespread species (114 isolations). In 55 cases (62%) M. bovis was associated with Pasteurella or Actinomyces (A.) pyogenes. The other mycoplasma species were found in 67 cases (42%) together with these bacteria. Without mycoplasmas Pasteurella and A. pyogenes occurred in 33 of the probes investigated (21%). Beside mycoplasmas Haemophilus (H.) somnus was isolated from 16 of 162 tracheobronchial secretions investigated. The results confirm earlier suppositions that in most of the cases bronchopneumonia of cattle is a multifactorial event, frequently associated with mycoplasmas--especially M. bovis.

Evidence for the existence of inositol tetrakisphosphate in mammalian heart. Effect of alpha 1-adrenoceptor stimulation

The time course of the effects of phenylephrine (10 mumol/l) on force of contraction and on inositol phosphates in electrically driven left auricles from rat hearts labeled with [3H]inositol was studied. All experiments were performed in the presence of propranolol (1 mumol/l) and LiCl (10 mmol/l). Products measured after separation with high-performance liquid chromatography were inositol 1-phosphate (1-IP1), inositol 1,4-bisphosphate (1,4-IP2), inositol 1,3,4-trisphosphate (1,3,4,-IP3), inositol 1,4,5-trisphosphate (1,4,5-IP3), and inositol 1,3,4,5-tetrakisphosphate (1,3,4,5-IP4). All inositol phosphates increased after stimulation with phenylephrine. 1,4,5-IP3 was the first compound to rise maximally within 30 seconds; this rise was followed by an increase in 1,3,4,5-IP4 and 1,4-IP2 beginning within 2 minutes. The increase in 1,3,4-IP3 and 1-IP1 was slower and did not reach steady state within 15 minutes. The positive inotropic effect of phenylephrine was maximal after 5 minutes. It is concluded that the increase in the presumed second messengers 1,4,5-IP3 and 1,3,4,5-IP4 coincides with the positive inotropic effect after alpha 1-adrenoceptor stimulation. Since the increase in 1,4,5-IP3 precedes the increase in force of contraction, 1,4,5-IP3 may initiate the positive inotropic effect of alpha 1-adrenoceptor agonists and 1,3,4,5-IP4 maintains the increase in force of contraction.

Molecular mechanisms of renin release

Renin secretion from renal juxtaglomerular cells is controlled by the intrarenal blood pressure, sodium chloride load of the organism, sympathetic nerve activity, and a number of hormones. The mechanisms by which these parameters exert their effects are not well understood. However, it is reasonable to assume that they act via signal transduction systems, implying the role of second messenger molecules in the control of renin secretion. This article summarizes present knowledge about the cellular mechanisms of renin secretion. Moreover, current concepts about the mechanisms by which the blood pressure and the sodium chloride load could influence renin secretion are discussed.

Mechanisms of positive inotropic effects

This review deals with the principal mechanisms which are known to play a role in positive inotropism: 1) The myoplasmic Ca2+ concentration may be increased by increases in cyclic AMP. Beside receptor-mediated stimulation (isoprenaline) or direct stimulation (forskolin) of the adenylate cyclase, the cyclic AMP may be increased by phosphodiesterase inhibition; 2) Cyclic AMP-independent activation of Ca2+ channels can be brought about by alpha-adrenergic agents (phenylephrine) or so-called calcium agonists; 3) Only a small increase in myoplasmic Na+ concentration can greatly enhance the force of contraction by an increase in the intracellular Ca2+ concentration. This is possible by inhibition of the Na+/K+-ATPase (glycosides) or by prolongation of the open state of Na+ channels (DPI 201-106); 4) A direct inhibition of the Na+/Ca2+ exchange has been discussed for amiloride; 5) A prolongation of the action potential induced by K+ channel-inhibiting agents such as 4-amino-pyridine may increase the myoplasmic Ca2+ concentration by a prolongation of the slow Ca2+ inward current; 6) An increased Ca2+ sensitivity of the contractile proteins has been demonstrated for a number of compounds in vitro; the contribution of such an effect to the overall positive inotropism is unknown because a calcium sensitizer without any effects on calcium or sodium movements is not yet available.

Effects of adenosine analogues on contractile response and cAMP content in guinea-pig isolated ventricular myocytes

In the present study the effects of adenosine analogues were investigated on cAMP content and contractile response in guinea-pig ventricular myocytes. The adenosine analogues (-)-N6-phenylisopropyladenosine (R-PIA), 5'-N-ethylcarboxamideadenosine (NECA) and (+)-N6-phenylisopropyladenosine (S-PIA) in the presence of 0.01 mumol/l isoprenaline reduced contractile response concentration-dependently. R-PIA and NECA were about equipotent (IC25: 0.01 mumol/l and 0.039 mumol/l respectively), while S-PIA was less potent (IC25: 0.6 mumol/l). Isoprenaline stimulated cAMP content was reduced by R-PIA (IC25: 0.004 mumol/l) and with lower potency by S-PIA (IC25: 0.15 mumol/l), but the extent of reduction of cAMP by R-PIA and S-PIA (to 55% and 64% respectively) was less than the reduction of contractile response (to 26% and 55% respectively). This suggests that the effects of R- and S-PIA on contractile response are only in part due to a reduction in cAMP content. In addition, NECA did not decrease cAMP content but decreased contractile response to the same extent as R-PIA. Similar results were obtained in the presence of the phosphodiesterase inhibitor Ro 20-1724. Time course studies revealed that the effects of R-PIA (1 mumol/l) on cAMP content and contractile response coincided reaching steady state after 5 min and remained stable thereafter. The effects of NECA (1 mumol/l) on contractility also reached steady state within 5 min, whereas it did not change cAMP content. It is concluded that the reduction of contractility by adenosine analogues in the presence of isoprenaline can only in part be explained by a reduction of cAMP content.(ABSTRACT TRUNCATED AT 250 WORDS)

On the mechanism of positive inotropic effects of alpha-adrenoceptor agonists

The positive inotropic effect of the alpha 1-adrenoceptor agonist phenylephrine is accompanied by an increase in the presumed second messengers inositol 1,4,5-trisphosphate (1,4,5-IP3) and inositol 1,3,4,5-tetrakisphosphate (1,3,4,5-IP4). Both 1,4,5-IP3 and 1,3,4,5-IP4 sensitize myocardial contractile proteins in chemically skinned fibers. In addition to the Ca++ releasing effect of 1,4,5-IP3 from the sarcoplasmic reticulum the Ca++-sensitizing effect of the inositol phosphates may play a role in alpha 1-adrenergic positive inotropism. In isolated heart muscle preparations from patients with endstage heart failure (due to dilated cardiomyopathy) beta-adrenergic as well as alpha 1-adrenergic effects are reduced compared to preparations from healthy hearts. The reduced beta-adrenergic effects can in part be explained by an increased content of signal transducing G1-proteins. It is tempting to investigate whether other G proteins are also altered in severe congestive heart failure.

[Methods for the elucidation of epidemics of salmonella infections limited to the alimentary tract]

The authors demonstrate results and experience to the methodology of epidemic focus investigations in identification of food causing infections, basing on the evaluation of four Salmonella outbreaks in the district of Gera in 1986 and 1987. The main tasks are: careful anamnestic registration of food and dishes consumed by affected people and persons in the community during the relevant incubation period with help of a check-list, case findings in several stages, continuous documentation of the results in the check-list, analytic evaluation of this list, operative control measures in food-producing factories and super-markets suspected to be a source of infection, microbiologic examinations in men, food, and environment.

Erythropoietin in polycystic kidneys

Erythropoietin (EPO) formation in kidneys of 18 patients with autosomal dominant polycystic kidney disease (ADPKD) was investigated. In 12 patients on hemodialysis and in 6 patients with preterminal renal failure serum, EPO was 29 +/- 7 and 16 +/- 1.5 mU/ml and hemoglobin concentrations were 11.0 +/- 0.6 and 12.7 +/- 1.2 g/dl, respectively. Cyst fluid from a total of 357 renal cysts was obtained by either in vivo aspiration or immediately after nephrectomy. The cysts contained variable concentrations of bioactive EPO from undectable values up to 3.2 U/ml. A pronounced enrichment of EPO was observed in cysts with sodium concentrations greater than 100 mmol/liter, suggesting an association with proximal tubular malformations. The EPO concentrations in the cysts were neither correlated with the protein concentration nor with the oxygen pressure of the cyst fluid. Using a cDNA probe for human EPO, mRNA for EPO was localized in stroma cells of the cyst walls by an in situ hybridization technique. Our findings suggest that single interstitial cells juxtaposed to proximal tubular cysts may produce EPO independent of the oxygen pressure inside the cysts, which ameliorates the anemia during end-stage polycystic kidney disease.

Effects of 1,3-dipropyl-8-cyclopentylxanthine (DPCPX), a highly selective adenosine receptor antagonist, on force of contraction in guinea-pig atrial and ventricular cardiac preparations

The effects of the A1 adenosine receptor antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX) on force of contraction were examined in isolated electrically driven auricles and papillary muscles from guinea-pigs in the absence and presence of (-)-N6-phenylisopropyladenosine (PIA) and 5'-N-ethylcarboxamidadenosine (NECA). In auricles DPCPX (30-1000 mmol/l) alone increased force of contraction. DPCPX produced only a minor inhibition of phosphodiesterase I-III activity. PIA and NECA alone exerted concentration-dependent negative inotropic effects and the concentration-response curves for PIA and NECA were shifted competitively to the right by the adenosine receptor antagonist DPCPX with similar potency and efficacy. The pA2-value for the inhibition of the effects of PIA and NECA were 9.1 and 8.8, respectively. In papillary muscles DPCPX alone had no inotropic effect. In the presence of isoprenaline PIA and NECA alone exerted concentration-dependent negative inotropic effects and again DPCPX shifted the concentration-response curves for PIA and NECA competitively to the right with similar potency and efficacy. The pA2-value for the inhibition of the effects of PIA and NECA were 9.3 and 9.0, respectively. It is concluded that DPCPX is a potent competitive A1 adenosine receptor antagonist in guinea-pig atrial and ventricular cardiac preparations. Since PIA and NECA were equally potent the cardiac adenosine receptor may constitute a subtype of A1 adenosine receptors differing from the receptor in other tissues such as fat cells. Furthermore, DPCPX has a positive inotropic effect in atrial tissue which cannot be attributed to the A1 receptor antagonism.