IN VITRO CELLULAR DYNAMICS BY RADIOAUTOGRAPHY: CALCIUM-45 IN RAT SALIVARY GLANDS

¹ Physiologisches Institut, Heidelberg, Germany; Department of Pharmacology, Stanford University School of Medicine, Stanford, California

Rat submaxillary and sublingual glands were found to accumulate ⁴⁵Ca in a saline medium in a manner similar to that found in vivo when studied by radioautography. Acinar cells showed intense uptake as compared to tubule cells, but this intense uptake was limited to a zone 250 to 300 µ from the surface of the tissue with a sharp line of demarcation . The in vitro accumulation of ⁴⁵Ca was altered markedly by metabolic inhibition and by acetyicholine and isoproterenol. Both of these drugs abolished the difference in uptake between acinar cells and tubule cells. Acetylcholine reduced the depth of intense uptake to 100 to 150 µ and isoproterenol reduced the depth of intense uptake to 150 to 200 µ. In addition, in the presence of acetylcholine, a punctate uptake of ⁴⁵Ca occurred which could not be associated readily with a particular cell type. Metabolic inhibition by cold and cyanide abolished the line of demarcation between intense uptake of ⁴⁵Ca in the surface layer and less uptake in deeper layers and brought about greater uptake in tubule cells as compared to acinar cells.