You can set this from api-manager.xml. Under APIGateway section there's the GatewayEndpoint element in which you can specify the URLs which should be shown in the store.
<APIGateway>
<Environments>
<Environment type="hybrid">
<Name>Production and Sandbox</Name>
<ServerURL>https://localhost:9445/services/</ServerURL>
<Username>admin</Username>
<Password>admin</Password>
**<GatewayEndpoint>http://localhost:8282,https://localhost:8245</GatewayEndpoint>**
</Environment>
</Environments>
<EnableGatewayKeyCache>true</EnableGatewayKeyCache>
<ClientDomainHeader>referer</ClientDomainHeader>
</APIGateway>