The aim of the present study is to compare two kinds of acute stress upon cardiovascular system and monoamines content in heart and adrenals. The first one was a cold stress (CS): each rat was placed in a cold room (4 o C) for 3 hours. The second one was a jet of air (JA) blowed in a plexiglass test chamber for 10 minutes. Arterial blood pressure and heart rate were recorded in 5 rats before and after CS, by means of a catheter implanted in the right carotid artery, two days before. Noradrenaline (NA) and serotonin (5-HT) in heart, adrenaline (AD) and NA in adrenal medulla were determined by a HPLC-EC method.Acute CS did not change arterial blood pressure, but produced a significant tachycardia (357 +/- 16 vs 398 +/- 11 bpm) (p < 0.05). These parameters were not recorded during JA stress, but the same results are reported by Lundin and Thoren (1).Cardiac NA was unchanged: 0.504 +/- 0.02 ng/mg (Control) vs 0.471 +/- 0.03 ng/mg (CS) and 0.451 +/- 0.03 ng/mg (JA).Cardiac 5-HT was lowered only in CS: 0.201 +/- 0.04 ng/mg (Control) vs 0.069 +/- 0.03 ng/mg (CS) (p < 0.05) and 0.179 +/- 0.03 ng/mg (JA).Total adrenal AD content was unchanged: 20.45 +/- 1.29 μg (Control) vs 19.37 +/- 0.47 μg (CS) and 21.41 +/- 2.88 μg (JA) neither adrenal NA content: 5.78 +/- 0.48 μg (Control) vs 6.59 +/- 0.25 μg (CS) and 6.81 +/- 0.68 μg (JA).While many authors reported a stress-induced increase in plasma catecholamines after stress, our results show that the basal pool is not modified by these two kinds of acute stress. The role of cardiac 5-HT in cold stress remains unclear.