According to Bhāgavatapurāṇa (Bhagavatapurana), Prāṇa(Prana) was one of Aṣṭavasu (Astavasu; Eight Vasus). Āyu was the son of Prāṇa and Ūrjasvatī (Urjaswati).

Bhāgavatpurāṇa Vols. 1-12(6.6.12)