Our results suggest that felypressin has equipotent pressure responses when compared with epinephrine, showing a greater extent of action. Atenolol's reduction of hypertensive effects surprisingly suggests that atenolol β-blockade may also be important for felypressin's cardiovascular effect, as is widely known for epinephrine. Our data suggest that felypressin is safe for hypertensive subjects, in particular those receiving atenolol.

Background: Cigarette smoking is usually associated with hypertension and may modify vasoconstrictor response. Objective:The present study aimed to analyze and compare the interaction of passive cigarette smoking and hypertension on epinephrine and felypressin blood pressure effects after intravascular injection.Method: 45-day male Wistar rats had the main left renal artery partially constricted and the right kidney removed (1K1C model). Rats were placed in the chamber for exposition to passive cigarette smoking (10 cigarettes) during 10 min (6 days a week). Hypertensive rats received atenolol (90 mg/kg/day) by gavage for two weeks. Hypotensive and hypertensive response, response duration and heart rate were recorded from direct blood pressure values. The significance level was 5%.Results: Passive cigarette smoking increased maximal hypertensive response to epinephrine in normotensive and 1K1Catenolol treated rats and to felypressin only in 1K1C-atenolol treated rats; it also reduced epinephrine hypotensive response. Epinephrine increased heart rate in normotensive and hypertensive passive smokers or non-smoker rats. Comparing the two vasoconstrictors, epinephrine showed greater hypertensive response in normotensive smokers, 1K1C-atenolol treated smokers and non-smokers. However, in normotensive-nonsmoker rats, felypressin showed a greater and longer hypertensive effect. Conclusions:Our results suggest that passive cigarette smoking may reduce epinephrine vasodilation and increase hypertensive response when compared to felypressin. Therefore, felypressin may be safe for hypertensive patients to avoid tachycardia and atenolol interaction, but for normotensive and non-smoker patients, epinephrine may be safer than felypressin.

This study aimed to evaluate changes in blood pressure of rats treated or not with amitriptyline after infiltration in the buccal sulcus and intravenous injection of epinephrine, felypressin and phenylephrine in equivalent doses (ED) to the amounts present in 2, 8 and 32 local anesthetic tubes. 42 male Wistar rats, with 45-day-old, treated for seven days with amitriptyline hydrochloride (0.3 mg/kg). On the eighth day, the animal was submitted to general anesthesia and surgery for direct blood pressure rate. The significance level was 5%. The treatment with amitriptyline caused a significant decrease in blood pressure of the treated group compared to the control group (101.80 ± 2.52 and 110.12 ± 2.91 mmHg, respectively, * p < 0.05), and slightly potentiates the hypertensive response after infiltration of epinephrine (4.11 ± 0.54; 7.15 ± 0.55; 9.03 ± 0.87 mmHg, respectively, 2, 8 and 32 tubes, p > 0.05). Felypressin promotes lower blood pressure changes and phenylephrine proved to be the most potent vasoconstrictor of the three studied, producing important changes in blood pressure and, even though infiltration, in doses greater than 8 tubes (15.43 ± 1.15; 70.62 ± 3.70 mmHg, respectively, 8 and 32 tubes, * p < 0.05). The infiltration of the three vasoconstrictors in doses equal to or less than 8 tubes does not cause significant changes in blood pressure, both in the control and amitriptyline treated groups.