Regulation of Ca2+-dependent K+-channel activity in tracheal myocytes by phosphorylation

Isoprenaline is a beta-adrenergic agonist of clinical importance as a remedy for asthma. In airway smooth muscle its relaxant action is accompanied by hyperpolarization of the membrane and elevation of the level of intracellular cyclic AMP. Hyperpolarization and relaxation are also induced by drugs such as forskolin, theophylline and dibutyryl cAMP, indicating that cAMP-dependent phosphorylation is involved in producing the electrical response. Cyclic AMP-dependent protein kinase (protein kinase A) has been reported to activate Ca2+-dependent K+ channels in cultured aortic smooth muscle cells and snail neurons. The membrane of tracheal smooth-muscle cells is characterized by a dense distribution of Ca2+-dependent K+-channels. We have now examined the effect of isoprenaline and protein kinase A on Ca2+-dependent K+-channels in isolated smooth muscle cells of rabbit trachea, using the patch-clamp technique. Our results show that the open-state probability of Ca2+-dependent K+-channel of tracheal myocytes is reversibly increased by either extracellular application of isoprenaline or intracellar application of protein kinase A. We also show that this effect is significantly enhanced and prolonged in the presence of a potent protein phosphatase inhibitor, okadaic acid.     

Vitamin A and tumor immunity

Summary Intraperitoneal administration of vitamin A into the BALB/c mice inoculated with a syngeneic fibrosarcoma, Meth A, caused a remarkable augmentation of tumor rejection. A cell-depletion technique revealed that the primary effector cells responsible for the augmented rejection were Thy-1 positive, Lyt-1 negative, Lyt-2 positive lymphocytes, suggesting the involvement of cytotoxic lymphocytes.This work was supported in part by a Grant-in-Aid for scientific research from the Ministry of Education, Science and Culture, Japan, and in part by a Grant-in-Aid for cancer research from the Fukuoka Cancer Society, Japan.We thank Mr M. Fujiki and Miss A. Maeda for excellent technical assistance.     

The physiology of the smooth muscle: an interdisciplinary review—part II

Summary In the guinea pig taenia coli, when glycogen is depleted by repeating Ca-induced contracture in excess K solution containing no glucose, the tension cannot be maintained. The decrease in tension is accompanied by reduction of high energy phosphate compounds and oxygen consumption. When substrate is readmitted to the glycogendepleted preparation in the presence of 2.4 mM Ca and 20 mM K, the first response is hyperpolarization of the membrane and relaxation, and this is followed by depolarization and development of contracture. The latter response is blocked by verapamil, suggesting that energy supply increases the Ca conductance of the plasma membrane. The early response is considered to be due to activation of electrogenic Ca pump, since this is not affected by ouabain as well as removal of Na and K. ATP produced by substrate readmission is probably preferentially utilized for Ca pump activation to reduce the intracellular. Ca. The recovery of tension is likely to be brought about by ATP supply not only to the contractile machinery but also to the plasma membrane to remove inactivation of Ca conductance. It is postulated that as the energy source is depleted, energy consumption is automatically limited by suppressing Ca influx, as a selfdefence mechanism. Since HB is as effective as glucose in the recovery of these processes, and also in the activation of electrogenic Na pump, the matabolic pathway of oxidative phosphorylation alone can support these functions without a contribution of the glycolytic pathway.     

KNOWLEDGE PROCESS ANALYSIS： FRAMEWORK AND EXPERIENCE

We present a step-by-step approach for constructing a framework for knowledge process analysis （KPA）. We intend to apply this framework to the analysis of own research projects in an exploratory way and elaborate it through the accumulation of case studies. This study is based on a methodology consisting of knowledge process modeling, primitives synthesis, and reflective verification. We describe details of the methodology and present the results of case studies： a novel methodology, a practical work guide, and a tool for KPA; insights for improving future research projects and education; and the integration of existing knowledge creation theories.     

An aspartic acid repeat polymorphism in asporin inhibits chondrogenesis and increases susceptibility to osteoarthritis

Osteoarthritis is the most common form of human arthritis. We investigated the potential role of asporin, an extracellular matrix component expressed abundantly in the articular cartilage of individuals with osteoarthritis, in the pathogenesis of osteoarthritis. Here we report a significant association between a polymorphism in the aspartic acid (D) repeat of the gene encoding asporin (ASPN) and osteoarthritis. In two independent populations of individuals with knee osteoarthritis, the D14 allele of ASPN is over-represented relative to the common D13 allele, and its frequency increases with disease severity. The D14 allele is also over-represented in individuals with hip osteoarthritis. Asporin suppresses TGF-beta-mediated expression of the genes aggrecan (AGC1) and type II collagen (COL2A1) and reduced proteoglycan accumulation in an in vitro model of chondrogenesis. The effect on TGF-beta activity is allele-specific, with the D14 allele resulting in greater inhibition than other alleles. In vitro binding assays showed a direct interaction between asporin and TGF-beta. Taken together, these findings provide another functional link between extracellular matrix proteins, TGF-beta activity and disease, suggesting new therapeutic strategies for osteoarthritis.     

Diaryl pyrroles: A new series of anti-inflammatory agents

Zusammenfassung Die antiinflammatorischen Eigenschaften von verschiedenen Diaryl-pyrrol-Derivaten wurden untersucht. Es wurde festgestellt, dass eine repräsentative Verbindung, 2-Methyl-4, 5-bis(p-metoxyphenyl)-pyrrol, eine ausgeprägte Hemmung gegen das akute Ödem und die chronische Arthritis der Ratte zeigt.

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We thank Messrs.K. Wachi, Y. Umemuro andT. Kojima for their technical assistance.     

Inhibition of riboflavin-sensitized photoinactivation of taka-amylase a by some inhibitors

Zusammenfassung Durch Gegenwart von Co⁺⁺ oder J^– oder Tryptophan oderp-Phenylendiamin wird die durch Riboflavin sensibilisierte Photoinaktivierung der Taka-Amylase A stark gehemmt. Die möglichen Mechanismen der Hemmungswirkung dieser Inhibitoren werden diskutiert.     

Binding of ferritin-lectin conjugates to C-type virus in intact cells

Summary Ferritin-Ricin II and Ferritin-Concanavalin A bound to budding as well as mature C-type viral particles. No differencies in binding between the viral coat and adjacent plasma membrane were detected with either lectin conjugate. Aggregation of viral particles by lectin conjugates was observed, and linking of virus to the plasma membrane resulted in phagocytosis of viral particles.Acknowledgment. The authors thank Phyllis Johnson for her excellent technical assistance. This work was supported by NIH grant CA 15044-03 and NS 06208. LM is the recipient of an NINDS Research Career Development Award 1 KO4-NS 00101.