The Japanese journal of physiology
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Using an X-ray television system, we directly measured the changes in internal diameter (ID; 100-600 microns) of small pulmonary arteries and veins in response to intravenous infusion of atrial natriuretic peptide (ANP) in anesthetized rabbits and cats. Under physiological conditions, ANP (0.01-1 micrograms/(kg.min) for 3 min) increased the ID of the small arteries in a dose-dependent manner by 4-9% and by 6-14% in the rabbit and cat, respectively. The maximum increase in ID occurred in the 400-600 microns arteries. ⋯ In the small veins, however, no significant vasodilation occurred even under the elevated-tone conditions. We concluded that ANP dilates the arterial segments in the rabbit and cat pulmonary microcirculation selectively and in a dose-dependent manner. Furthermore, the pulmonary vasodilator effect of ANP was dependent on the pulmonary vascular tone.
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The origin of the 0.1 Hz bursting of cultured rat cortical neurons in zero Mg2+ was studied by whole-cell recording, fluo-3 Ca2+ imaging, and multi-unit electrode array recording. A model is proposed in which spontaneous synaptic currents act as a random pacemaker.