Slow intercellular Ca(2+) signaling in wild-type and Cx43-null neonatal mouse cardiac myocytes.

Focal mechanical stimulation of single neonatal mouse cardiac myocytes in culture induced intercellular Ca(2+) waves that propagated with mean velocities of approximately 14 micrometer/s, reaching approximately 80% of the cells in the field. Deletion of connexin43 (Cx43), the main cardiac gap junction channel protein, did not prevent communication of mechanically induced Ca(2+) waves, although the velocity and number of cells communicated by the Ca(2+) signal were significantly reduced. Similar effects were observed in wild-type cardiac myocytes treated with heptanol, a gap junction channel blocker. Fewer cells were involved in intercellular Ca(2+) signaling in both wild-type and Cx43-null cultures in the presence of suramin, a P(2)-receptor blocker; blockage was more effective in Cx43-null than in wild-type cells. Thus gap junction channels provide the main pathway for communication of slow intercellular Ca(2+) signals in wild-type neonatal mouse cardiac myocytes. Activation of P(2)-receptors induced by ATP release contributes a secondary, extracellular pathway for transmission of Ca(2+) signals. The importance of such ATP-mediated Ca(2+) signaling would be expected to be enhanced under ischemic conditions, when release of ATP is increased and gap junction channels conductance is significantly reduced.

[Meeting reports in the Nederlands Tijdschrift voor Geneeskunde; value for readers and associations]. / De verenigingsverslagen in het Nederlands Tijdschrift voor Geneeskunde; het nut voor lezers en verenigingen.

OBJECTIVE: To determine the objective of scientific association proceedings in the Nederlands Tijdschrift voor Geneeskunde (NTvG) and whether the objective is met by publication. DESIGN: Interview. SETTING: The editorial office of NTvG MATERIAL AND METHODS: The clinical relevancy of the proceedings published in 1990 and 1991 was determined using selection criteria. 53 (former) secretaries of scientific associations which publish their proceedings in NTvG were interviewed by written questionnaire, and 101 physicians were interviewed by telephone, asking for their opinion on the objective and the use of publishing the proceedings. RESULTS: Of the proceedings (1610 abstracts) published in 1990 and 1991 20% were considered clinically relevant. The opinion of the secretaries of the associations was that the objective of the proceedings is to record medical information and to provide a medical newspaper for the latest reports of the associations, mostly intended for all readers of the NTvG. The secretaries usually correct the abstracts with respect to form and to a lesser extent to informative value. Editorial office selection of the abstracts was not considered desirable, guidelines with regard to writing an abstract of the proceedings were appreciated. More than half of the family physicians read the proceedings, but often considered them too specialised. Half of these thought editorial office selection of the abstracts advisable. About 80% of the specialists read the proceedings, of which the informative value was considered variable. They disapproved of editorial selection. In general physicians read the proceedings very selectively. CONCLUSIONS: The clinical relevancy of the abstracts of the proceedings leaves much to be desired. The objective is to provide a medical record and a newspaper for all readers, but these read the proceedings very selectively. The informative value could be improved. Abstract selection should be in the hands of the associations' secretaries only, but guidelines from the editorial office on writing abstracts are welcomed.