Table 1: Influence of ISO and normal IgG atria on prostaglandins production in rat isolated atria. Values are mean ± SEM of six experiments in each case performed by duplicate. * P< 0.001 ISO vs. Basal; ** P< 0.01 ISO vs. ISO + atenolol.
ADDITIONS	Concentration of Prostaglandins (ng/ml)
	Normoxia		Hypoxia
	PGE₂	6-Keto- PGF_1α	PGE2	6-Keto- PGF_1α
Basal	4.7± 0.3	5.1± 0.4	5.8 ± 0.5	5.9 ± 0.5
ISO (1x10^-7 M)	9.7± 0.6*	16.7± 1.3*	14.6 ± 1.3*	16.9± 1.5*
ISO + atenolol (1x10^-7 M)	3.8 ± 0.4**	5.7± 0.6**	7.3 ± 0.6**	5.4± 0.5**
Normal IgG (1x10^-8 M)	4.8 ± 0.4	5.3± 0.7	5.9 ± 0.6	5.9± 0.7