Receptor-mediated biological effects of extracts obtained from three Asplenium species.

This study reports the effects of aqueous extracts obtained from three fern species of Bulgarian origin: Asplenium ceterach L., Asplenium scolopendrium L., and Asplenium trichomanes L. on the contractility and bioelectrogenesis of rat gastric smooth muscle tissues. In the concentration range 0.015-0.150 mg/mL the three extracts contracted smooth muscle tissues in a concentration-dependent manner. The contractions caused by A. ceterach L. and A. scolopendrium L. extracts (0.150 mg/mL) were reduced by ketanserin (5 × 10-7 and 5 × 10-6 mol/L), an antagonist of serotonin 5-HT2 receptor. The contraction evoked by A. trichomanes L. (0.150 mg/mL) was significantly reduced by 1 × 10-6 mol/L atropine, an antagonist of muscarinic receptors, and turned into relaxation against the background of 3 × 10-7 mol/L galantamine. After combined pretreatment with galantamine and l-arginine (5 × 10-4 mol/L), this relaxation become more pronounced. The study demonstrates that constituents of A. ceterach L. and A. scolopendrium L. extracts act as agonists of 5-HT2 receptors and cause contraction by activating serotonergic signaling system. A. trichomanes L.-induced reaction is an additive result of two opposite-in-character effects. The dominant contraction is initiated by inhibition of acetylcholinesterase activity. The relaxation develops with pre-inhibited acetylcholinesterase, it is significantly potentiated by l-arginine, and therefore associated with nitrergic signaling pathway.

Study on in Vivo Pial Vessels Alterations and Activity of Isolated Vascular Smooth Muscles in Abdominal Hypertension Rats.

BACKGROUND: Intra-abdominal hypertension is known as a factor affecting cerebral haemodynamics. Sustainably elevated abdominal pressure may disturb the balance of intracranial/blood pressure ratio, eventually developing perfusion pressure to drop. AIM: The aim of this study is to investigate the influence of artificially elevated intra-abdominal pressure upon brain pial vessels condition and contractile reactivity of isolated rat arteria carotis communis and vena jugularis to norepinephrine and serotonin. MATERIALS AND METHODS: The abdominal pressure of rats anaesthetized with xylazine 10 mg/kg and ketamine 100 mg/kg was increased up to 25 mm Hg by insufflation of air through venflon cannula and maintained for period of 1 to 3 hours. Craniotomy of left parietal area was carried out by micro drill. Open scull and cranial window techniques were applied. Outer diameters of superficial pial vessels were measured by USB digital microcamera (magnification up to 400x). Contractile reactivity of smooth muscle preparations from arteria carotis communis and vena jugularis of euthanized abdominal-hypertensive (AH) rats was registered isometrically. RESULTS: Increased smooth muscle reactivity of a. carotis communis from AH rats to serotonin (10-8-10-4 mol/l) but not to norepinephrine compared to controls was registered. The changes tended to be higher in long lasting (3 hours) exposure of AH rats. Increase in outer diameter of pial vessels during maintenance of abdominal hypertension in both open scull and cranial window techniques was found. CONCLUSIONS: The increased intra-abdominal pressure causes dilatation of small superficial cerebral blood vessels and increases the smooth muscle reactivity of isolated arteria carotis communis to 5-HT.