Transport of somatostatin and substance P by human P-glycoprotein |
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Authors: | Uchiyama-Kokubu Noriko Naito Mikihiko Nakajima Motowo Tsuruo Takashi |
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Affiliation: | Novartis Pharma K.K., Tsukuba Research Institute, Okubo 8, Tsukuba, Ibaraki 300-2611, Japan. noriko.uchiyama@pharma.novartis.com |
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Abstract: | P-glycoprotein is an efflux pump for a broad spectrum of hydrophobic agents. We found that bioactive peptides including somatostatin and substance P inhibit ATP-dependent vincristine binding to P-glycoprotein-overexpressing K562/ADM membrane vesicles. Some of these bioactive peptides including somatostatin stimulate basal ATPase activity of P-glycoprotein; in contrast, other peptides including substance P inhibit it. The K562/ADM membrane vesicles showed an ATP-dependent, osmotically sensitive uptake of somatostatin and substance P, which was inhibited by valspodar, an inhibitor of P-glycoprotein. These findings suggested that certain bioactive peptides such as somatostatin and substance P directly interact with human P-glycoprotein as endogenous substrates for P-glycoprotein-mediated transport. |
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