{"id":{"repo_id":"aachen","oai_identifier":"oai:publications.rwth-aachen.de:52116"},"canonical_url":"https://search.dev.ndltd.org/etd/aachen/oai:publications.rwth-aachen.de:52116","repository":{"repo_id":"aachen","name":"RWTH Aachen University","base_url":"https://publications.rwth-aachen.de/oai2d"},"display":{"title":"Charakterisierung des Gallensäuretransporters ASBT am Oozyten-Expressionssystem","abstract":"In the present study investigations on the bile acid transporter ASBT (apical bile acid transporter) have been conducted. This transporter physiologically occurs in the apical cell membrane of cholangiocytes, ileocytes and cells of the proximal tube of the kidney. It is among other essential for the re uptake of bile acids due to the course of enterohepatic circulation. The cRNA of the ASBT was injected in oocytes of Xenopus laevis and successful expression was verified by Wester-Blot analysis. As a well established substrate of the bile salt transporter taurocholic acid was chosen for the experiments. With the first experiments we were able to show that the treatment with the micro injector was no problem regarding the leaking of the oocytes’ membrane as there was no elevated taurocholic acid uptake of the buffer-injected oocytes compared to the untreated oocytes. Due to these first experiments we also were able to show that the oocyte of the African clawed frog doe not have any endogenous transport mechanisms for bile acid uptake and that the bile acid uptake of the micro injected oocytes is strictly depending on sodium. Highest correlation was obtained by assuming taurocholate to sodium ratio of one: two. This clearly opposes the previous theory of a electro neutral transport. Time dependence of taurocholate uptake into oocytes illustrated a constantly increasing uptake for three hours. Dependence of the taurocholate uptake on the taurocholate concentration showed a soluble transport ratio. Transformation of the data according to Eadie Hofstee revealed a KM= 32,02 µM and a Vmax= 139 pmol / oocyte / 30min and by the computer program “Curffit” a KM= 41,84 µM and a Vmax= 146,23 pmol / oocyte / 30min. These kinetic parameters were firstly obtained from experiments with oocytes and matched generally the data published in literature. Also firstly investigated was the inhibitory effect of DMSO on the taurocholic acid uptake of the ASBT. With a concentration of one percent the taurocholate uptake decreased significantly. The specific ASBT-inhibitor S 0960 decreased in it’s highest concentration the taurocholate uptake by 60%. Also for the first time in oocytes the regulation of the ASBT by the protein kinase A (PKA) has been studied with the activator of the adenylat cyclase Forskolin, the phosphodiesterase inhibitor IBMX, the cAMP-analogon 8-bromo-cAMP and the specific PKA-inhibitor H 89. Although in literature it is proven that the ASBT underlies the regulation of the PKA, we were not able to obtain this kind of data. To reveal the regulation of the ASBT by PKA there will have to be further investigation, since regarding this topic there only exists one paper so far. In order to do so one will have to use a different experimental method than the use of oocytes of Xenopus laevis.","abstract_html":"In the present study investigations on the bile acid transporter ASBT (apical bile acid transporter) have been conducted. This transporter physiologically occurs in the apical cell membrane of cholangiocytes, ileocytes and cells of the proximal tube of the kidney. It is among other essential for the re uptake of bile acids due to the course of enterohepatic circulation. The cRNA of the ASBT was injected in oocytes of Xenopus laevis and successful expression was verified by Wester-Blot analysis. As a well established substrate of the bile salt transporter taurocholic acid was chosen for the experiments. With the first experiments we were able to show that the treatment with the micro injector was no problem regarding the leaking of the oocytes’ membrane as there was no elevated taurocholic acid uptake of the buffer-injected oocytes compared to the untreated oocytes. Due to these first experiments we also were able to show that the oocyte of the African clawed frog doe not have any endogenous transport mechanisms for bile acid uptake and that the bile acid uptake of the micro injected oocytes is strictly depending on sodium. Highest correlation was obtained by assuming taurocholate to sodium ratio of one: two. This clearly opposes the previous theory of a electro neutral transport. Time dependence of taurocholate uptake into oocytes illustrated a constantly increasing uptake for three hours. Dependence of the taurocholate uptake on the taurocholate concentration showed a soluble transport ratio. Transformation of the data according to Eadie Hofstee revealed a KM= 32,02 µM and a Vmax= 139 pmol / oocyte / 30min and by the computer program “Curffit” a KM= 41,84 µM and a Vmax= 146,23 pmol / oocyte / 30min. These kinetic parameters were firstly obtained from experiments with oocytes and matched generally the data published in literature. Also firstly investigated was the inhibitory effect of DMSO on the taurocholic acid uptake of the ASBT. With a concentration of one percent the taurocholate uptake decreased significantly. The specific ASBT-inhibitor S 0960 decreased in it’s highest concentration the taurocholate uptake by 60%. Also for the first time in oocytes the regulation of the ASBT by the protein kinase A (PKA) has been studied with the activator of the adenylat cyclase Forskolin, the phosphodiesterase inhibitor IBMX, the cAMP-analogon 8-bromo-cAMP and the specific PKA-inhibitor H 89. Although in literature it is proven that the ASBT underlies the regulation of the PKA, we were not able to obtain this kind of data. To reveal the regulation of the ASBT by PKA there will have to be further investigation, since regarding this topic there only exists one paper so far. In order to do so one will have to use a different experimental method than the use of oocytes of Xenopus laevis.","abstract_has_math":false,"creators":["Riehl, Stephan"],"institution":"Publikationsserver der RWTH Aachen University","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["Greven, Joachim"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2006,"date_issued":"2006","date_published":"2006","updated_at":"2026-07-30T19:40:50Z","subjects":["info:eu-repo/classification/ddc/610","Medizin"],"languages":["ger"],"rights":["info:eu-repo/semantics/openAccess"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-114357%22"],"render_values":[{"text":"https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-114357%22","href":"https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-114357%22","code":true}]}]},"links":{"outbound_url":"https://publications.rwth-aachen.de/record/52116","outbound_label":"Repository record","outbound_source":"dc:identifier"},"source_record":{"url":"https://publications.rwth-aachen.de/oai2d?verb=GetRecord&metadataPrefix=oai_dc&identifier=oai%3Apublications.rwth-aachen.de%3A52116","prefix":"oai_dc"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Greven, Joachim"]},{"key":"dc:creator","label":"Author","values":["Riehl, Stephan"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:coverage","label":"Dc Coverage","values":["DE"]},{"key":"dc:date","label":"Dc Date","values":["2006"]},{"key":"dc:publisher","label":"Institution","values":["Publikationsserver der RWTH Aachen University"]},{"key":"dc:relation","label":"Dc Relation","values":["info:eu-repo/semantics/altIdentifier/urn/urn:nbn:de:hbz:82-opus-16221"]},{"key":"dc:type","label":"Dc Type","values":["info:eu-repo/semantics/doctoralThesis","info:eu-repo/semantics/publishedVersion"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["info:eu-repo/classification/ddc/610","Medizin"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["ger"]},{"key":"dc:rights","label":"Dc Rights","values":["info:eu-repo/semantics/openAccess"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://publications.rwth-aachen.de/record/52116","https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-114357%22"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["In the present study investigations on the bile acid transporter ASBT (apical bile acid transporter) have been conducted. This transporter physiologically occurs in the apical cell membrane of cholangiocytes, ileocytes and cells of the proximal tube of the kidney. It is among other essential for the re uptake of bile acids due to the course of enterohepatic circulation. The cRNA of the ASBT was injected in oocytes of Xenopus laevis and successful expression was verified by Wester-Blot analysis. As a well established substrate of the bile salt transporter taurocholic acid was chosen for the experiments. With the first experiments we were able to show that the treatment with the micro injector was no problem regarding the leaking of the oocytes’ membrane as there was no elevated taurocholic acid uptake of the buffer-injected oocytes compared to the untreated oocytes. Due to these first experiments we also were able to show that the oocyte of the African clawed frog doe not have any endogenous transport mechanisms for bile acid uptake and that the bile acid uptake of the micro injected oocytes is strictly depending on sodium. Highest correlation was obtained by assuming taurocholate to sodium ratio of one: two. This clearly opposes the previous theory of a electro neutral transport. Time dependence of taurocholate uptake into oocytes illustrated a constantly increasing uptake for three hours. Dependence of the taurocholate uptake on the taurocholate concentration showed a soluble transport ratio. Transformation of the data according to Eadie Hofstee revealed a KM= 32,02 µM and a Vmax= 139 pmol / oocyte / 30min and by the computer program “Curffit” a KM= 41,84 µM and a Vmax= 146,23 pmol / oocyte / 30min. These kinetic parameters were firstly obtained from experiments with oocytes and matched generally the data published in literature. Also firstly investigated was the inhibitory effect of DMSO on the taurocholic acid uptake of the ASBT. With a concentration of one percent the taurocholate uptake decreased significantly. The specific ASBT-inhibitor S 0960 decreased in it’s highest concentration the taurocholate uptake by 60%. Also for the first time in oocytes the regulation of the ASBT by the protein kinase A (PKA) has been studied with the activator of the adenylat cyclase Forskolin, the phosphodiesterase inhibitor IBMX, the cAMP-analogon 8-bromo-cAMP and the specific PKA-inhibitor H 89. Although in literature it is proven that the ASBT underlies the regulation of the PKA, we were not able to obtain this kind of data. To reveal the regulation of the ASBT by PKA there will have to be further investigation, since regarding this topic there only exists one paper so far. In order to do so one will have to use a different experimental method than the use of oocytes of Xenopus laevis."]},{"key":"dc:source","label":"Dc Source","values":["Aachen : Publikationsserver der RWTH Aachen University 100 S. : Ill., graph. Darst. (2006). = Aachen, Techn. Hochsch., Diss., 2006"]},{"key":"dc:title","label":"Title","values":["Charakterisierung des Gallensäuretransporters ASBT am Oozyten-Expressionssystem"]}]}],"canonical_facts":{"dc:contributor":["Greven, Joachim"],"dc:coverage":["DE"],"dc:creator":["Riehl, Stephan"],"dc:date":["2006"],"dc:description":["In the present study investigations on the bile acid transporter ASBT (apical bile acid transporter) have been conducted. This transporter physiologically occurs in the apical cell membrane of cholangiocytes, ileocytes and cells of the proximal tube of the kidney. It is among other essential for the re uptake of bile acids due to the course of enterohepatic circulation. The cRNA of the ASBT was injected in oocytes of Xenopus laevis and successful expression was verified by Wester-Blot analysis. As a well established substrate of the bile salt transporter taurocholic acid was chosen for the experiments. With the first experiments we were able to show that the treatment with the micro injector was no problem regarding the leaking of the oocytes’ membrane as there was no elevated taurocholic acid uptake of the buffer-injected oocytes compared to the untreated oocytes. Due to these first experiments we also were able to show that the oocyte of the African clawed frog doe not have any endogenous transport mechanisms for bile acid uptake and that the bile acid uptake of the micro injected oocytes is strictly depending on sodium. Highest correlation was obtained by assuming taurocholate to sodium ratio of one: two. This clearly opposes the previous theory of a electro neutral transport. Time dependence of taurocholate uptake into oocytes illustrated a constantly increasing uptake for three hours. Dependence of the taurocholate uptake on the taurocholate concentration showed a soluble transport ratio. Transformation of the data according to Eadie Hofstee revealed a KM= 32,02 µM and a Vmax= 139 pmol / oocyte / 30min and by the computer program “Curffit” a KM= 41,84 µM and a Vmax= 146,23 pmol / oocyte / 30min. These kinetic parameters were firstly obtained from experiments with oocytes and matched generally the data published in literature. Also firstly investigated was the inhibitory effect of DMSO on the taurocholic acid uptake of the ASBT. With a concentration of one percent the taurocholate uptake decreased significantly. The specific ASBT-inhibitor S 0960 decreased in it’s highest concentration the taurocholate uptake by 60%. Also for the first time in oocytes the regulation of the ASBT by the protein kinase A (PKA) has been studied with the activator of the adenylat cyclase Forskolin, the phosphodiesterase inhibitor IBMX, the cAMP-analogon 8-bromo-cAMP and the specific PKA-inhibitor H 89. Although in literature it is proven that the ASBT underlies the regulation of the PKA, we were not able to obtain this kind of data. To reveal the regulation of the ASBT by PKA there will have to be further investigation, since regarding this topic there only exists one paper so far. In order to do so one will have to use a different experimental method than the use of oocytes of Xenopus laevis."],"dc:identifier":["https://publications.rwth-aachen.de/record/52116","https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-114357%22"],"dc:language":["ger"],"dc:publisher":["Publikationsserver der RWTH Aachen University"],"dc:relation":["info:eu-repo/semantics/altIdentifier/urn/urn:nbn:de:hbz:82-opus-16221"],"dc:rights":["info:eu-repo/semantics/openAccess"],"dc:source":["Aachen : Publikationsserver der RWTH Aachen University 100 S. : Ill., graph. Darst. (2006). = Aachen, Techn. Hochsch., Diss., 2006"],"dc:subject":["info:eu-repo/classification/ddc/610","Medizin"],"dc:title":["Charakterisierung des Gallensäuretransporters ASBT am Oozyten-Expressionssystem"],"dc:type":["info:eu-repo/semantics/doctoralThesis","info:eu-repo/semantics/publishedVersion"]},"updated_at":"2026-07-30T19:40:50Z"}