I was reading stories of Samudra Manthan in Bhagavata Purana. It has been described that, Indra had insulted sage Durvasa and was cursed in return to loose all his material opulence.
That time, they also started losing battle with asuras and some devas getting killed in battle. Samudra manthan was done to extract nectar to make them immortal.
Following link says that, it happened in Chakshusha Manvantara, with Mantradruma as Indra. http://vedabase.com/sb/8/5/en.
Does it mean that, previously all devas were NOT immortal?
What about in current manvantara ?