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H Haase

Publications and source records attributed to H Haase.

At least 73 records · Page 4Linked to original sources
PubMed1996

Contraction kinetics and myosin isoform composition in smooth muscle from hypertrophied rat urinary bladder.

Mechanical properties and isoform composition of myosin heavy and light chains were studied in hypertrophying rat urinary bladders. Growth of the bladder was induced by partial ligation of the urethra. Preparations were obtained after 10 days. In maximally activated skinned preparations from the hypertrophying tissue, the maximal shortening velocity and the rate of force development following photolytic release of ATP were reduced by about 20 and 25%, respectively. Stiffness was unchanged. The relative content of the basic isoform of the essential 17 kDa myosin light chain was doubled in the hypertrophied tissue. The expression of myosin heavy chain with a 7 amino acid insert at the 25K/50K region was determined using a peptide-derived antibody against the insert sequence. The relative amount of heavy chain with insert was decreased to 50% in the hypertrophic tissue. The kinetics of the cross-bridge turn-over in the newly formed myosin in the hypertrophic smooth muscle is reduced, which might be related to altered expression of myosin heavy or light chain isoforms.

Adenosine Triphosphate↗
PubMed1996

Expression of calcium channel subunits in the normal and diseased human myocardium.

We investigated the expression of alpha1 and beta subunits of the L-type Ca2+ channel on the protein level in cardiac preparations from normal human heart ventricles and from the hypertrophied septum of patients with hypertrophic obstructive cardiomyopathy (HOCM). 1,4-Dihydropyridine (DHP) binding and immunorecognition by polyclonal antibodies directed against the C-terminal amino acid sequences of the beta2 and beta3 subunits were used for detection and quantification of alpha1, beta2, and beta3 subunits. Bmax of high-affinity DHP binding was 35 +/- 2 fmol/mg protein in HOCM and 20 +/- 2 fmol/mg protein in normal human hearts (P<0.05). In rabbit hearts the anti-beta2 subunit antibody immunoprecipitated 80% of the total amount of DHP-labeled Ca2+ channels present in the assay. Under identical experimental conditions 25% of labeled Ca2+ channels were recovered in the immunoprecipitates of both normal and HOCM ventricles. A similar partial immunoprecipitation was observed in pig hearts. Immunoblot analysis demonstrated that the beta2 subunit was associated with the DHP receptor/Ca2+ channel in cardiac muscle of rabbit, pig, and human heart. In neither of these purified cardiac Ca2+ channels was the beta3 subunit isoform detected. Our results suggest that both alpha1 and beta2 subunit expression is upregulated in HOCM in a coordinate manner.

Amino Acid Sequence↗
PubMed1995

Cyclic GMP-mediated phospholamban phosphorylation in intact cardiomyocytes.

The cGMP-mediated phospholamban phosphorylation was investigated in cardiomyocytes in response to receptor-dependent (atrial natriuretic peptide, ANP) and -independent (sodium nitroprusside; SNP) cGMP generation. ANP (1 nM-1 microM) induced phospholamban phosphorylation in a concentration-dependent fashion (EC50: 5.0 +/- 0.09 nM). Concomitantly, an elevation in cGMP levels was observed. Phospholamban was also dose-dependently phosphorylated in response to SNP, but it required about three orders of magnitude higher concentrations (EC50: 2.9 +/- 0.03 microM) than ANP. Treatment of the cells with 8Br-cGMP (10 microM) or with the specific activator of cGMP-protein kinase 8-pCPT-cGMP (1-100 microM) mimicked these effects. The results demonstrate for the first time that a ANP/cGMP signaling pathway exists in neonatal cardiomyocytes which may contribute to modulation of heart contractility.

Animals↗
PubMed1995

Steroid-hormone regulation of myosin subunit expression in smooth and cardiac muscle.

We investigated the effects of ovarectomy and the steroid hormones estrogen and testosterone on the in vivo expression of heavy (MHC) and light (MLC) chains of myosin in the heart, uterus, and aorta of rats. In the heart, ovarectomy decreased alpha-MHC expression, while both steroid hormones normalized it. Differential steroid hormone effects could be observed on myosin subunit expression of smooth muscle. Testosterone but not estrogen normalized the ovarectomy-induced decreased expression of SM1 and strongly increased the expression of 5'-inserted MHC in the uterus. Estrogen but not testosterone normalized the ovarectomy-induced diminished MLC17a expression. In contrast to the uterus, no steroid hormone effects on myosin subunit expression could be observed in the aorta.

Amino Acid Sequence↗
PubMed1994

Detection of skeletal muscle calcium channel subunits in cultured neonatal rat cardiac myocytes.

A monoclonal antibody (mAb) 8B7, that recognizes specifically the alpha 1-subunit of dihydropyridine-sensitive calcium channels in skeletal muscle, exerted a dose-dependent positive chronotropic effect on cultured spontaneously beating neonatal rat cardiac myocytes. The antibody-induced increase in beating frequency was similar to that elicited by 1 microM of (-)-isoprenaline. The mAb 8B7 recognized a polypeptide that is analogous to the 170-kDa calcium channel alpha 1-subunit of rabbit skeletal muscle in wheat germ lectin purified proteins solubilized from cultured rat heart myocytes by Western blot analysis. Furthermore, the mAb 7C3, previously shown to recognize specifically the skeletal muscle calcium channel beta-subunit, reacted with a 55-kDa polypeptide in these cultured myocytes. No immunoreactivity, however, was obtained when proteins solubilized from both neonatal or adult rat heart tissue were employed in Western blotting or immunoprecipitation experiments. RNA-hybridization analysis revealed that primary cultures derived from neonatal rat hearts expressed two types of mRNA encoding the skeletal muscle as well as the cardiac calcium channel alpha 1-subunit, while neonatal rat heart tissue expressed only the message for cardiac calcium channel. These results provide evidence for a functional expression of skeletal muscle-type calcium channel subunits during the cultivation of neonatal rat heart cells.

Animals↗
PubMed1993

Phosphorylation of the L-type calcium channel beta subunit is involved in beta-adrenergic signal transduction in canine myocardium.

Cyclic AMP-mediated phosphorylation of calcium channel subunits was studied in vitro and in vivo in preparations from dog heart. Calcium channels in native cardiac membranes were phosphorylated by cAMP-dependent protein kinase (PKA) solubilized with digitonin and subsequently immunoprecipitated using a polyclonal antibody generated against the deduced carboxy-terminal sequence of the cardiac beta subunit. A 62 kDa protein was identified as the major PKA-substrate in the immunoprecipitates. In the intact myocardium, this putative beta subunit was found to be phosphorylated in response to cAMP elevating agents. In contrast, no phosphorylation of a protein with an electrophoretic mobility similar to the alpha 1 subunit was detected, although 1,4-dihydropyridine receptor sites were recovered in the immunoprecipitates. Thus, we suggest that PKA-mediated phosphorylation of the beta subunit is the major mechanism for beta-adrenergic regulation of cardiac L-type calcium channel activity.

Amino Acid Sequence↗
PubMed1991

A rapid procedure for the purification of cardiac 1,4-dihydropyridine receptors from porcine heart.

Highly purified porcine cardiac sarcolemma was used as a source for purification of mammalian cardiac 1,4-dihydropyridine receptors associated with the voltage-dependent Ca2+ channel. The cardiac digitonin-solubilized receptor prelabeled with (+)-[3H]PN 200-110 was enriched at least 236-fold using an improved, rapid three-step purification protocol which could be completed within 12 h. The purity of the preparation was at least 22%, the yield of the receptors 24%. Photoaffinity labeling experiments with (-)-[3H]azidopine allowed the identification of the cardiac alpha 1 subunit. In contrast to the purified rabbit or guinea-pig skeletal muscle Ca2+ channel complex, none of the purified polypeptides underwent rapid and substantial phosphorylation by the catalytic subunit of the cyclic AMP-dependent protein kinase in vitro.

Affinity Labels↗
PubMed1987

Evaluation of electrical potential difference across gastric mucosa in patients with chronic gastritis according to site, histology, and degree of inflammation.

The electrical potential difference (PD) of gastric mucosa was measured under direct endoscopic visualization in 39 patients. Seventy-six observations were made, 39 in fundic mucosa and 37 in the antral region. Biopsies taken from these areas allowed the identification of a control group and a gastritis group. The PD measurements of the control group were higher in the fundic mucosa (P less than 0.001) than in the antral region. In the gastritis group, PD measurements both in the fundic and antral regions were lower than those of the control group (P less than 0.01). However, in the gastritis group, PD measurements of the fundic region were still higher (P less than 0.01) than the PD of the antral region. The correlation coefficient of PD measurements versus the semiquantitative assessment of oxyntic and chief cells of the fundus was r = 0.49 (P less than 0.01).

Adult↗
PubMed1987

The visual stress model--a psycho-physiological method for the evaluation of operational reliability of pilots and cosmonauts.

An experimental psycho-physiological method is presented for the evaluation of visual-cognitive performance preconditions and operational reliability of pilots and cosmonauts. As visual-cognitive stress are used tachistoscopically presented instrument symbols under conditions of individual speed of work and time pressure. The results of the compared extreme groups consisting of pilots with good and insufficient flight performance showed that the pilots with impairments to the quality of flight activity differ already before the test in their individual habitual characteristics and actual motivation, during the stress in their operational parameters, in the dimensions of their cardiorespiratory activation as well as in their efficiency and after the stress in their subjective experience of the stress. Conclusions are drawn for the evaluation of the aptitude of pilots and cosmonauts.

Adolescent↗
PubMed1987

Characterization of calcium antagonist receptors in highly purified porcine cardiac sarcolemma.

Drug receptors for the Ca-antagonists nitrendipine and (-)desmethoxyverapamil (D-888) were studied in porcine cardiac sarcolemma. The dihydropyridine (DHP) derivative [3H]nitrendipine binds to a single population of high affinity sites (KD = 0.44 +/- 0.10 nM, Bmax = 2.43 +/- 0.19 pmol/mg; (n = 8), whereas the phenylalkylamine derivative [3H](-)D-888 interacts with high and low affinity sites of KD = 5.1 +/- 1.4 nM and KD = 438 +/- 86 nM (n = 6) in the same membrane preparations. The antagonists tested differ also with respect to their pharmacological efficacy on cultured intact heart myocytes. The EC50 value of the negative chronotropic effect exerted by D-888 corresponds to its high affinity binding component. Nitrendipine exhibit a 200-fold lower pharmacological efficacy, as would be expected from binding data.

Animals↗
PubMed1987

Isoproterenol induces both cAMP- and calcium-dependent phosphorylation of phospholamban in canine heart in vivo.

The phosphorylation state of phospholamban in hearts of dogs depleted from catecholamines or treated with isoproterenol has been characterized using a sensitive back-phosphorylation method that allows to distinguish between cAMP-dependent and Ca2+/calmodulin-dependent phosphorylation occurring at the protein in situ. The data obtained demonstrate that in response to the beta-adrenergic agonist isoproterenol both the cAMP-dependent and the Ca2+/calmodulin-dependent phosphorylatable site are phosphorylated suggesting a physiological significance also for Ca2+-dependent phosphorylation of phospholamban in canine heart in vivo.

Animals↗
PubMed1987

Fast activation of Ca2+-ATPases in plasma membranes from cardiac muscle and from ascites carcinoma cells: a possible function of endogenous calmodulin.

Content of endogenous calmodulin, binding of calmodulin to, and Ca2+-ATPase activity in plasma membranes of cardiac muscle. Ehrlich ascites carcinoma (EAC) cells and erythrocytes were examined. The content of endogenous calmodulin in cardiac and EAC cells was shown to be considerably higher than in erythrocyte membranes. Ca2+-independent binding of calmodulin to cardiac and EAC cell membranes was found to be realized by some low molecular weight proteins. Ca2+-ATPases in cardiac and EAC cell membranes differ from those in erythrocytes with respect to their activation by Ca2+ and calmodulin. The erythrocyte enzyme is strongly stimulated by exogenous calmodulin and reaches its maximum activity about 2 min after Ca2+-addition. In contrast, the Ca2+-ATPases in cardiac and EAC cell plasma membranes cannot be considerably stimulated by exogenous calmodulin and are instantaneously activated by Ca2+.

Animals↗
PubMed1986

Oxygen regimen in the human peripheral tissue during space flights.

A survey of the results of the experiment "Oxygen," carried out within the scope of the INTER-KOSMOS program in members of the permanent crews and of international visiting expeditions to the Soviet orbital station Salyut-6, is given. During the 7-day space flights of the international visiting expeditions a significant decrease in pO2ic by 3.28 kPa was observed. Local oxygen utilization reduced significantly by 0.44 kPa. During hyperventilation testing after return to earth a statistically significant decrease in the peak value by 1.39 kPa was noted. In the long-term crews of the orbital station Salyut-6 the highest decrease in pO2ic of 3.8 kPa and the absolutely lowest value of 3.4 -/+ 0.5 kPa during space flight were observed. The decrease in local oxygen utilization during the flight of 0.8 kPa/min was greater than that of the visiting crews. The results indicate the importance of investigating the dynamics of the oxygen regimen for medical control of the crew members both during the space flight and during the readaptation phase after return to earth.

Adaptation, Physiological↗
PubMed1986

Putative Ca2+ channels in cardiac membranes. Subcellular distribution of [3H]nitrendipine receptors.

The binding of Ca2+ channel blocking drug nitrendipine was studied in purified sarcolemma (SL), fragmented sarcoplasmic reticulum (SR), and crude membranes isolated from porcine left ventricle. The density of specific [3H]nitrendipine binding sites was compared to Na+/Ca2+ exchange and (Na+, K+)ATPase activities of each membrane preparation. Enrichment of [3H]nitrendipine binding sites in purified SL correlates excellently with the purification of the two studied sarcolemmal marker activities. The results suggest that high affinity nitrendipine receptors are solely localized in cardiac SL.

Animals↗