ABSTRACT
Here, we report on a novel experimental apparatus for performing time-resolved soft x-ray absorption spectroscopy in the sub-ns time scale using non-hybrid multi-bunch mode synchrotron radiation. The present setup is based on a variable repetition rate Ti:sapphire laser (pump pulse) synchronized with the ~500 MHz x-ray synchrotron radiation bunches and on a detection system that discriminates and singles out the significant x-ray photon pulses by means of a custom made photon counting unit. The whole setup has been validated by measuring the time evolution of the L(3) absorption edge during the melting and the solidification of a Ge single crystal irradiated by an intense ultrafast laser pulse. These results pave the way for performing synchrotron time-resolved experiments in the sub-ns time domain with variable repetition rate exploiting the full flux of the synchrotron radiation.
Subject(s)
Sick Sinus Syndrome/complications , Wolff-Parkinson-White Syndrome/complications , Adult , Aged , Arrhythmias, Cardiac/complications , Child, Preschool , Electrocardiography , Female , Humans , Male , Middle Aged , Prognosis , Sick Sinus Syndrome/diagnosis , Wolff-Parkinson-White Syndrome/diagnosisABSTRACT
In order to investigate the cardiovascular effects of ATP (15-30 mg) i.v. administration, 12 normal subjects, aged 27-55 yrs, were studied, during Arterial Pressure Monitoring and His Bundle Electrogram recording, using Sherlag's technique. ATP cardiovascular response was divided in the following four phases: Latency phase, Progressive Bra dyarrhythmic-Hypotensive, Maximal Inhibitor Phase, Tachyarrhytthmic Hypotensive Reflex Phase. Atropine (0.02-0.04 mg/Kg) i.v. injection did not significantly prevent ATP effects. Increasing dosage of atropine (0,06, pointed out a moderate competitive antagonism with ATP. These data suggest a possible direct action of ATP (purinergic receptors or direct membrane effect) but don't exclude an interaction with Parasympathetic system (probable purinergic neuromodulation).