Biological research
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Biological research · Jan 2006
Association of nicotinic acetylcholine receptors with central respiratory control in isolated brainstem-spinal cord preparation of neonatal rats.
Nicotine exposure is a risk factor in several breathing disorders Nicotinic acetylcholine receptors (nAChRs) exist in the ventrolateral medulla, an important site for respiratory control. We examined the effects of nicotinic acetylcholine neurotransmission on central respiratory control by addition of a nAChR agonist or one of various antagonists into superfusion medium in the isolated brainstem-spinal cord from neonatal rats. Ventral C4 neuronal activity was monitored as central respiratory output, and activities of respiratory neurons in the ventrolateral medulla were recorded in whole-cell configuration. ⋯ Dihydro-beta-erythroidine induces hyperpolarization and decreases intraburst firing frequency of inspiratory and preinspiratory neurons. In contrast, methyllycaconitine has no effect on the membrane potential of inspiratory neurons, but does decrease their intraburst firing frequency while inducing hyperpolarization and decreasing intraburst firing frequency in preinspiratory neurons. These findings indicate that alpha4beta2 nAChR is involved in both inspiratory and preinspiratory neurons, whereas alpha7 nAChR functions only in preinspiratory neurons to modulate C4 respiratory rate.
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Biological research · Jan 1999
ReviewVasopressin and bradykinin receptors in the kidney: implications for tubular function.
Vasopressin and bradykinin are two of the most important peptides in regulating vascular tone, water, and ionic balance in the body, and thus they play a key role in controlling blood pressure. In addition to being a potent vasoconstrictor, Vasopressin also has an antidiuretic activity in the kidney, whereas kinins regulate renal blood flow in addition to their vasodilatory and natriuretic activity. We review here the primary evidence for the localization of the vasopressin and kinin receptors and their role in ionic and water regulation in the kidney.
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Biological research · Jan 1995
ReviewThe activation of bulbo-spinal controls by peripheral nociceptive inputs: diffuse noxious inhibitory controls.
Some neurones in the dorsal horn of the spinal cord are strongly inhibited when a nociceptive stimulus is applied to any part of the body, distinct from their excitatory receptive fields. This phenomenon was termed "Diffuse Noxious Inhibitory Controls" (DNIC). DNIC influence only convergent neurones, and these inhibitions can be triggered only by conditioning stimuli which are nociceptive. ⋯ In other words, the descending inhibitory controls may play a physiological role in the detection of nociceptive signals. It is proposed that DNIC constitute both a filter which allows the extraction of the signal for pain and an amplifier in the transmission system which increases the potential alarm function of the nociceptive signals. This hypothesis is supported by the finding that DNIC are blocked by low doses of morphine in both rat and man.
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In memoriam Professor Hugo Adrian, born 1926, deceased 1994, in Santiago, Chile. After completion of his studies in veterinary medicine, he followed a successful career in neurophysiological research. He was Research Associate (1961-1962) and Visiting Professor (1973-1976) at the Neurophysiology Department University of Wisconsin, USA. He was the first Director (1958-1960) of the Institute of Physiology at the Austral University, Valdivia, and was Professor (1963-1973; 1977-1994) and Chairman of the Department of Physiology and Biophysics, University of Chile, Santiago, Chile, where he led a group of researchers in auditory physiology, introduced the use of computer techniques to physiological studies, and developed several projects of applied neurophysiology.