ADORA2A and hereditary elliptocytosis: In addition, Varani et al. report that the intake of caffeine (400 or 600 mg/day for one week or 400 mg/d for two weeks) may upregulate A2A adenosine receptor activity, increase cAMP accumulation and anti-aggregatory effects, and decrease calcium levels elicited by HE-NECA in a time-dependent and dose-dependent manner [97].