Role of purinoceptors in cardiac function in rats during ontogeny

Intravenous injection of exogenous ATP (10(-4) M) to rats aging 21, 56, and 100 days increased the heart rate by the 15th sec postinjection. Stable ATP analogue alpha,beta-methylene-ATP in an equimolar concentration increased the heart rate in rats aging 56 and 100 days (by the 15th second after treatment), but had no effect on 21-day-old animals. alpha,beta-Methylene-ATP in a concentration of 10(-7) M increased the heart rate in 21-day-old rat pups, which attests to high sensitivity of P2 purinoceptors. Administration of ATP and alpha,beta-methylene-ATP after treatment with nonselective purinoceptor antagonist suramin did not increase the heart rate in rats of different age groups. Infusion of ATP and its stable analogue after administration of selective P2Y receptor antagonist reactive blue 2 increased the heart rate in rats of different age groups. These changes reflect activation of P2X receptors in the heart.