Surface characteristics of carbonic-anhydrase-rich cells in turtle urinary bladder

Surface characteristics of carbonic-anhydrase-rich cells in turtle urinary bladder. Addition of a disulfonic stilbene, 4-acetamido-4′-isothiocyano-2,2′-disulfonic stilbene (SITS), to the serosal side of the turtle bladder blocks the efflux of bicarbonate ions from the acidifying cells and thereby inhibits hydrogen ion secretion into the luminal solution. Because SITS has little effect on other transport systems, we used it to define the relationship between hydrogen ion secretion (J H ) and the different cell types facing the luminal surface. Cells were identified by scanning and transmission electron microscopy (SEM and TEM) and by histochemical localization of carbonic anhydrase (CA). SEM revealed that SITS caused marked alterations in luminal surface characteristics of a cell population with prominent microplicae. Two hours after the serosal addition of SITS, cells with identifiable microplicae had decreased from 12.7 to 0.5% of total cells. TEM studies and CA histochemistry showed that the number of cells rich in CA (CA cells) remained the same, whereas the individual luminal surface areas of a subpopulation of CA cells had decreased markedly. A comparison of the distribution of individual surface areas of cells with microplicae and CA cells revealed that the CA cells with large surface areas corresponded to the cells with microplicae and that both were affected by the serosal addition of SITS. Acetazolamide, which also inhibits J H caused similar changes. The luminal addition of SITS and an inactive analogue of acetazolamide, which have no effect on J H did not alter surface morphology. These results indicate that the CA cell with microplicae represents the active state of the hydrogen ion secreting cell. Caracteristiques de surface des cellules riches en anhydrase carbonique de la vessie urinaire de tortue. L'action du stilbene disulfonique, 4-acetamido-4′-isothiocyano-2,2′-disulfonic stilbene (SITS), sur la face sereuse de la vessie de tortue bloque la secretion d'ions hydrogene vers la solution luminale. Du fait que le SITS a peu d'effets sur les autres systemes de transport il a ete employe pour definir la relation entre la secretion d'ions hydrogene (J H ) et les differents types cellulaires qui sont en regard de la surface luminale. Les cellules ont ete identifiees en microsco-pie electronique a balayage et ` transmission (SEM et TEM) et par la localisation histoenzymologique de l'anhydrase carbonique (CA). La SEM a montre que le SITS determine des modifications des caracteristiques de la surface luminale d'une population cellulaire a microplis proeminents. Deux heures apres l'addition sereuse de SITS, les cellules ayant des microplis identifiables ont diminue de 12,7 a 0,5% du nombre total de cellules. Les etudes au TEM et l'histochimie de CA montre que le nombre des cellules riches en CA (cellules CA) est le meme alors que la surface luminale d'une sous-population de cellules CA a considerablement diminue. Une comparaison de la distribution des surfaces individuelles des cellules a microplis et des cellules CA montre que les cellules CA a grande surface correspondent aux cellules a microplis et que les deux sont affectees par le SITS du cote sereux. L'acetazolamide, qui inhibe aussi J H , determine des modifications semblables. Le SITS luminal et un analogue inactif de l'acetazolamide qui n'a pas d'effet sur J H ne modifient pas la morphologie de surface. Ces resultats indiquent que les cellules CA a microplis representent l'etat actif de la cellule secretant d'ions hydrogene.