O.’Neill Angela E., Lumsden Amanda L. , Milsom William K.
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引用次数: 0
Abstract
In vertebrates, the basic respiratory rhythm is modified by both sensory feedback and input from higher centers to produce a broad range of breathing patterns. In carp (Cyprinus carpio L.), breathing is often episodic while in trout (Onchorhynchus mykiss) it is continuous and rhythmic except when water is hyperoxic. A previous study in carp revealed that stimulation of neurons at a site in the dorsal mesencephalic tegmentum (DMT) ventrolateral to the oculomotor nucleus, can terminate the apneas and initiate breathing episodes (Juch and Ballintijn, 1983). Such stimulation, however, did not eliminate the apneas or the breathing episodes. To determine whether this site also contains neurons involved in initiating periods of apnea that are intrinsic to episodic breathing, we attempted to lesion the DMT site in decerebrate, spinalectomized carp and trout using stereotaxic microinjections of 0.01 mM kainic acid. Following decerebration and spinalectomy, 93 % of carp and 33 % of trout breathed in episodes in hyperoxic water. Kainic acid injections initially stimulated breathing in all fish. As the excitotoxic effects progressed, breathing frequency and breath amplitude returned to normal levels suggesting that sites within the areas we lesioned are not involved in establishing the overall level of respiratory drive. The ensuing lesions, however, eliminated the episodic breathing in hyperoxia in over 50 % of the carp and 33 % of the trout. This suggests that sites within the midbrain tegmentum are involved in establishing breathing patterns and that there is a non-uniform distribution of neurons within the midbrain tegmentum involved in producing apneas and clustering breaths into episodes.
期刊介绍:
Respiratory Physiology & Neurobiology (RESPNB) publishes original articles and invited reviews concerning physiology and pathophysiology of respiration in its broadest sense.
Although a special focus is on topics in neurobiology, high quality papers in respiratory molecular and cellular biology are also welcome, as are high-quality papers in traditional areas, such as:
-Mechanics of breathing-
Gas exchange and acid-base balance-
Respiration at rest and exercise-
Respiration in unusual conditions, like high or low pressure or changes of temperature, low ambient oxygen-
Embryonic and adult respiration-
Comparative respiratory physiology.
Papers on clinical aspects, original methods, as well as theoretical papers are also considered as long as they foster the understanding of respiratory physiology and pathophysiology.