Polycationic effects on airways epithelia / by Michael D. Smith.
| Author/creator | Smith, Michael D. author. |
| Other author | Van Scott, Michael R., degree supervisor. |
| Other author | East Carolina University. Department of Biology. |
| Format | Theses and dissertations |
| Production | 1996. |
| Description | xiv, 121 leaves : illustrations ; 28 cm |
| Supplemental Content | Access via ScholarShip |
| Subjects |
| Summary | Protamine-induced changes in membrane bioelectric properties of human nasal (HNE), canine tracheal (CTE), and canine bronchial (CBE) epithelial cells were analyzed to evaluate the effects of polycations on Na+ absorption and CI- secretion. HNE cells bathed in Kreb's Bicarbonate Ringer (KBR) exhibited a hyperpolarization of the apical membrane voltage (Va) and no change in fractional resistance of the apical membrane (fRa) when protamine was added to the apical bath (100 (MU)g/ml). Following apical pretreatment with amiloride, protamine depolarized Va and decreased fRa. Protamine also depolarized HNE Va when the apical membrane was bathed in 3 mEq/L CI- solution. Regional differences in ion transport characteristics of canine airways epithelia allowed CI- secretory and Na+ absorptive cell types from the same lungs to be compared without external manipulation of membrane conductances and ion driving forces. Protamine depolarized Va in CTE cells which are intrinsically CI- secretory. In contrast protamine hyperpolarized Va and increased fRa in CBE cells. Freshly isolated CTE was mounted in Ussing chambers and bathed in KBR to further elucidate CI- channel subtypes involved in the polycationic augmentation of CI- secretion.. Incubation with 10-4 M bumetanide for 20 min. inhibited the Na+/K+/2CI- cotransport and subsequently decreased the baseline Isc. The Isc response to protamine was attenuated. Pretreatment with 10-5M isoproterenol and dibutyryl cAMP increased baseline Isc and inhibited the protamine response. Pretreatment with 0.5 mM ionomycin and ImM thapsigargin likewise increased baseline Isc attenuated the protamine-induced change in Isc. Inhibition of cyclooxygenase activity by pretreating with 1 mM indomethacin for 20 min. decreased baseline Isc by 50% but did not alter the response to protamine. Bilateral bathing of preparations in 75% KBR increased Isc via volume sensitive CP channels. Upon the addition of protamine a typical increase in Isc ensued. These results indicated that polycationic induced changes in ion transport across airway epithelia are dependent on the ion transport processes expressed by the cells at the time of exposure and that protamine induces CI- secretion through activation of latent cAMP sensitive elements in the apical membrane. |
| General note | Submitted to the faculty of the Department of Biology. |
| General note | Advisor: Michael R. Van Scott |
| Dissertation note | M.S. East Carolina University 1996 |
| Bibliography note | Includes bibliographical references (leaves 117-121). |
| Genre/form | Academic theses. |
| Genre/form | Academic theses. |
| Genre/form | Thèses et écrits académiques. |
Availability
| Library | Location | Call Number | Status | Item Actions |
|---|---|---|---|---|
| Joyner | University Archives | ASK AT SPECIAL COLLECTIONS DESK | ✔ Available | Request Material |
| Electronic Resources | Access Content Online | ✔ Available |