Ocimum gratissimum L. Leaf Enhances Relaxation Response to Acetylcholine without Inhibiting the Intrinsic Myogenic Tone in Wistar Rats’ Corpus Cavernosum Smooth Muscle

• S. A Shittu

• Y Raji

Ocimum gratissimum (OG) has been used as an aphrodisiac agent with no report on its effect in the modulation of corpus cavernosum relaxation process, hence this study. The effects of OG on acetylcholine responses were assessed in 12 Corpus Cavernosa Smooth Muscle (CCSM) obtained from 6 male Wistar rats. In an organ bath set-up, the CCSM were incubated in Krebs’ solution (control, n = 6) or Krebs’ solution containing OG (60 µg/mL, n = 6). The tissues were pre-contracted with potassium chloride (KCl, 60 mM), followed by graded doses of acetylcholine (10^-9 to 10^-5 M) and responses were recorded using an isometric force transducer and a data acquisition system connected to a computer. Mechanisms involved in the OG effects were then assessed by co-incubation with L-NAME, nifedipine, or Fasudil. Data were analysed using ANOVA at α0.05. Increased maximum relaxation response to acetylcholine was observed in OG-incubated CCSM (64.4±2.6%) compared with the control (47.6±3.4%). Co-incubation of OG with L-NAME (52.3±3.2%), nifedipine (56.8±2.9%) or Fasudil (52.3±1.6%) significantly reduced the relaxant effect of OG.  It was therefore concluded that Ocimum gratissimum leaf enhanced the relaxation response of corpus cavernosum to acetylcholine via modulation of calcium ion sensitivity. The intrinsic myogenic tone of the tissues was not inhibited by the relaxant-promoting activity of Ocimum gratissimum leaf.

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