Pharmacological Evidence of Hypotensive Activity of Somina (Herbal drug) in Normotensive Rats

Purpose: To evaluate the effects of somina (herbal drug) on the arterial blood pressure.
Methods: Hypotensive activity was studied in pentothal sodium-anesthetized normotensive albino rats at various doses of somina (5, 10, 15, 20 and 35 mg/kg). The drugs were administered intravenously and changes in arterial blood pressure (systolic, diastolic and mean arterial blood pressure) were registered directly from the carotid artery. Acetylcholine (Ach, 10^-4 M) was used as positive control for comparison while the receptor activity of Ach and somina was assessed using atropine (muscarinic receptor antagonist) on rat heart.
Results: Somina caused dose-dependent significant (p < 0.05) reduction in mean arterial pressure blood pressure (MABP). The 35 mg/kg dose caused 46.7 % fall in MABP, which was significant (p < 0.05) when compared with control. The results were comparable with those of acetylcholine (10^-4 M) which showed 45.6 % fall in MABP. For receptor activity, atropine (10^-4 M) was administered i.v., and then the Ach and somina (45 mg/kg) was administered one at a time. Non-significant fall in MABP was observed (1.2 and 20 %, p > 0.05) in rats that were pretreated with atropine.
Conclusion: Somina possesses potent hypotensive effect at different doses in normal rats by stimulating non-selective muscarinic receptors.

Keywords
Somina; Acetylcholine; Atropine; Herbal drug; Blood pressure; Hypotension activity; Muscarinic receptor; Vascular relaxant activity