Studies on antihypertensive and antispasmodic activities of methanol extract of Acacia nilotica pods.
A methanol extract of Acacia nilotica pods (AN) caused a dose-dependent (3-30 mg/kg) fall in arterial blood pressure. Treatment of animals with atropine abolished the vasodilator response of acetylcholine (ACh), whereas the antihypertensive effect of the plant extract remained unaltered. Phentolamine (an alpha-adrenergic blocker) abolished the vasoconstrictor effect of norepinephrine (NE), whereas pretreatment of the animal with AN, did not modify the NE response. These results indicate that the antihypertensive effect of plant extract is independent of muscarinic receptor stimulation or adrenoceptor blockade. In the in vitro studies, AN produced a dose-dependent (0.3-3.0 mg/mL) inhibitory effect on force and rate of spontaneous contractions in guinea-pig paired atria. Similarly, it inhibited the spontaneous contraction of rabbit jejunum in a concentration-dependent (0.1-3.0 mg/mL) manner. AN also inhibited K(+)-induced contractions in rabbit jejunum at a similar concentration range, which suggests that the antispasmodic action of AN is mediated through calcium channel blockade, and this may also be responsible for the blood pressure lowering effect of AN, observed in the in vivo studies.
Gilani
A H
AH
Department of Physiology and Pharmacology, The Aga Khan University Medical College, Karachi 47800, Pakistan. anwar.gilani@aku.edu
Shaheen
F
F
Zaman
M
M
Janbaz
K H
KH
Shah
B H
BH
Akhtar
M S
MS
D000045:Acacia / Q000737:chemistry*; D000109:Acetylcholine / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D000959:Antihypertensive Agents / Q000302:isolation & purification / Q000494:pharmacology*; D001285:Atropine / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005260:Female; D006168:Guinea Pigs; D006325:Heart Atria / Q000187:drug effects; D007583:Jejunum / Q000187:drug effects; D008297:Male; D000432:Methanol / Q000737:chemistry; D009119:Muscle Contraction / Q000187:drug effects*; D009638:Norepinephrine / Q000494:pharmacology; D010276:Parasympatholytics / Q000302:isolation & purification / Q000494:pharmacology*; D010646:Phentolamine / Q000494:pharmacology; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D011817:Rabbits; D051381:Rats; D017207:Rats, Sprague-Dawley; D012639:Seeds / Q000737:chemistry; D012702:Serotonin Antagonists / Q000494:pharmacology; D014599:Uterus / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects
D000317:Adrenergic alpha-Antagonists; D000959:Antihypertensive Agents; D002121:Calcium Channel Blockers; D010276:Parasympatholytics; D010936:Plant Extracts; D012702:Serotonin Antagonists; D001285:Atropine; D000109:Acetylcholine; D009638:Norepinephrine; D000432:Methanol; D010646:Phentolamine