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.

Changes in the Contractile Activity and Reactivity to 5-HT of Smooth Muscles of Rats Following Total Body Irradiation with Accelerated Electrons.

BACKGROUND: Besides its "classical" neurotransmitter function in the central and peripheral nervous systems, serotonin, or 5-hydroxytryptamine (5-HT) is also a local hormone in a number of tissues, including those of the GI tract. Radiation is known to be able to disrupt certain functions of the tract, modulated by 5-HT-signaling pathways, or the serotonin receptors themselves. AIM: The present investigation focused on clarifying the nature and extent of influence of an accelerated electron beam with energy of 9 MeV on the serotonergic mediation of healthy smooth muscle gastric tissue of rats following total body irradiation of the animals. MATERIALS AND METHODS: The study involved a control group and two experimental groups of animals exposed to 1 and 5 Gy, respectively, using Siemens Primus S/N 3561. Circular smooth muscle tissues were isolated from rats 1 hour and 18 hours after they were exposed to 1 and 5 Gy and also 5 days after irradiation from the rats that received a dose of 5 Gy in order to investigate the action of exogenous serotonin at increasing concentrations from 10-8 to 10-4 mol/l. The contractile reactivity of each group SM preparations was registered isometrically. RESULTS: Electron beams with energy of 9 MeV did not damage the contractile apparatus of gastric SM of rats and had a stimulating effect on contractility resulting from rapidly developing processes (1 hour) or later occurring once (5 days). CONCLUSIONS: Difference was observed in the importance of the factors of received dose, lapse of time from irradiation to investigation of SM tissues, and exogenous 5-HT concentration for the changes in SM reactivity in serotonin-induced tonic and phasic responses.