Miyako Mori

The effects of various peptides on the isolated pulmonary artery

Helical strips of pulmonary arteries from rabbits were tested for their responses to the following peptides: neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP), substance P (SP), cholecystokinin-octapeptide (CCK), somatostatin (SS), bombesin, neurotensin and gastrin. SP, in the absence of active base-tension, and NPY both induced concentration-dependent contractions, while VIP and SP, in the presence of active base-tone, and CCK induced relaxation. The pD2 (-log ED50) was in the order of NPY greater than SP and SP greater than CCK greater than VIP. SS, bombesin, NT and gastrin had no effect. These findings suggest peptidergic involvement in the vessels.

Endothelium-dependent relaxation in isolated pulmonary arteries from rabbits exposed to hyperoxia

The effects of hyperoxia and superoxide dismutase (SOD) administration on endothelium-dependent relaxation induced by acetylcholine in isolated rabbit pulmonary artery (PA) preparations were examined. Relaxation responses to papaverine, and contractile responses to KCl and norepinephrine were also assessed using a bioassay technique. Prolonged hyperoxia in rabbits for 3 days produced loss of endothelium-dependent relaxation of the PA, and significant attentuation of contractile response to KCl and relaxation response to papaverine. These changes were prevented by subcutaneous SOD administration. Histological examination using light and electron microscopy revealed focal edema, destruction, and detachment of the PA endothelium in the PA strip preparations from these rabbits. Thus, it is concluded that a high concentration of oxygen exposure in rabbits for 3 days produces not only histological damage in the PA endothelium, but also causes impairment of vascular reactivity to constricting and relaxing agents. Subcutaneous SOD administration prevented oxygen-induced PA damage.

Maturation-Related Changes in Dopamine-Induced Relaxation of Isolated Rabbit Pulmonary Artery

ABSTRACT: Studies were performed on isolated pulmonary arterial segments to investigate dopamine receptor-mediated relaxant effects at different times during development. Dopamine receptor-mediated relaxant effects can only be observed when vessels are precontracted with prostaglandin F2α and in the presence of α1, α2, and serotonergic blockade. Helical strips of pulmonary arteries from rabbits of different ages (2, 7, 14, 30, and 90 days), partially precontracted by prostaglandin F2α were tested for their responses to dopamine in the presence of prazosin (10-6 M), yohimbin (10-6 M), propranolol (10-6 M), and methysergide (10-6 M). Strips from 2– and 7-day-old rabbits were not induced to relax by dopamine, whereas those from 14–, 30–, and 90-day-old animals, after cumulative application of dopamine, underwent concentration-dependent relaxation. Dopamine (half the maximum response) concentration decreased during the development of rabbits from 14 to 90 days old. Mean values for apparent dopamine ED50 (half the maximum response) concentrations in the arteries of 14–, 30–, and 90-day old animals were 4.94 ± 0.40, 2.02 ± 0.30, and 0.113 ± 0.028 μM, respectively. The effects of various dopamine antagonists on dopamine-induced relaxation were not markedly different at different ages. These findings indicate that dopamine receptor function is not fully developed in the pulmonary arteries of newborn rabbits, but matures as the age of the rabbit increases.

The Efficacy of Aperiodic Analysis of the Electroencephalogram (EEG) during Anesthesia

Electroencephalogram (EEG) was the earliest electronic monitoring technique used in the operating room. Much work has validated their usefulness in the monitoring of the cerebral condition, and electroencephalographic changes have been shown to correlate well with cerebral blood flow.