Hello Madhu.
Apologies for delayed reply.
May I know your exact purpose?
There are certain tools as http://www.fivehundredplus.com/, which can be used to maintain the contacts list and prospects. It uses LinkedIn API.
You can also use some other tools as SocialMotus, HootSuite etc to send mass messages to multiple groups.
Please let me know if you have more questions, we will be happy to assist you further.
Regards,
-Gajanan