Development of central respiratory control in anurans: The role of neurochemicals in the emergence of air-breathing and the hypoxic response

Present address and address for reprint requests: Istituto di Scienze Farmacologiche, via Balzaretti 9, Università di Milano, Milano 20133, Italy. The role of sensory afferent information from the gills of Amia calva in cardiovascular and ventilatory control was investigated by bilateral branchial denervation and pseudobranch ablation. Aquatic hypoxia or 1 mg of sodium cyanide (NaCN) in the water flowing over the gills stimulated bradycardia, and gill and air ventilation in sham-operated fish. Sodium cyanide, noradrenaline (NA) and adrenaline (A) infusion into the dorsal aorta increased gill ventilation, and NA and A infusion also stimulated tachycardia and an increase in blood pressure. Following denervation and pseudobranch ablation, O2 consumption (V·OO2), airbreathing frequency (fAB) and arterial O2 tension (PaOO2) declined, and circulating NA levels increased, as compared with sham-operated fish. Cardiovascular and air-breathing responses to hypoxia were abolished and gill ventilatory responses attenuated. All ventilatory and cardiovascular responses to NaCN were abolished and gill ventilatory responses to NA and A were attenuated in animals following denervation and pseudobranch ablation. These results demonstrate that O2-sensitive chemoreceptors in the gills and pseudobranch control reflex bradycardia and air-breathing responses in Amia, but that gill ventilatory responses to hypoxia, NA and A are partially mediated by extrabranchial mechanisms. Plasma NA levels increased during hypoxia in shamoperated and denervated animals, indicating that circulating NA may have mediated gill ventilatory responses in denervated animals.

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Role of Substance P in Neutral Endopeptidase Modulation of Hypoxic Response of the Carotid Body

Oxygen Sensing - Advances in Experimental Medicine and Biology ◽

10.1007/0-306-46825-5_70 ◽

2002 ◽

pp. 705-713 ◽

Cited By ~ 9

Author(s):

Ganesh K. Kumara ◽

Yu Ru-Koub ◽

Jeffrey L. Overholtb ◽

Nanduri R. Prabhakarb

Keyword(s):

Substance P ◽

Carotid Body ◽

Neutral Endopeptidase ◽

Hypoxic Response

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Methylene blue potentiates vascular reactivity in isolated rat lungs

Journal of Applied Physiology ◽

10.1152/jappl.1989.66.3.1040 ◽

1989 ◽

Vol 66 (3) ◽

pp. 1040-1045 ◽

Cited By ~ 44

Author(s):

G. M. Mazmanian ◽

B. Baudet ◽

C. Brink ◽

J. Cerrina ◽

S. Kirkiacharian ◽

...

Keyword(s):

Methylene Blue ◽

Vascular Reactivity ◽

Bolus Injection ◽

Pressor Response ◽

Hypoxic Response ◽

Pressor Responses ◽

Isolated Rat Lung ◽

Lung Preparation ◽

Isolated Rat

A bolus injection of methylene blue (1 mg), a guanylate cyclase inhibitor, or aspirin (3 mg) in the isolated rat lung preparation had little or no effect on resting perfusion pressure under normoxic condition. In contrast, methylene blue markedly potentiated hypoxic vasopressor response (4-fold) when injected before or during the alveolar hypoxic stimulation. Hemoglobin also potentiated the hypoxic pressor response. Similarly, methylene blue or aspirin augmented the pressor responses to angiotensin II (0.1–1 microgram). The increased hypoxic response induced by methylene blue was immediate and sustained. Methylene blue, when added during hypoxia in the presence of aspirin, further augmented the response to hypoxia compared with the enhanced hypoxic response observed with aspirin alone. Our results suggest that, in addition to the role of cyclooxygenase products, the pulmonary vascular bed may be regulated by endothelium-dependent factors that can be antagonized directly or indirectly by methylene blue.

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Role of ATP in respiratory control and active transport in tobacco hornworm midgut

AJP Cell Physiology ◽

10.1152/ajpcell.1980.238.1.c10 ◽

1980 ◽

Vol 238 (1) ◽

pp. C10-C14 ◽

Cited By ~ 34

Author(s):

L. J. Mandel ◽

T. G. Riddle ◽

J. M. Storey

Keyword(s):

Active Transport ◽

Respiratory Control ◽

Intermediate Form ◽

Decay Kinetics ◽

Kinetic Rates ◽

Fresh Frozen ◽

The Difference ◽

Redox Level ◽

K Transport

The intracellular ATP, ADP, AMP, and orthophosphate (Pi) levels were measured in the midgut of Manduca sexta. The nucleotide levels were identical in tissues either “fresh” frozen or equilibrate in regular (32 mM) K or low (8 mM) K solutions. The calculated [ATP]/[ADP][Pi]ratio was approximately 300 M-1, which is low compared to other tissues. Given the ability of this ratio to control the respiratory rate, it is speculated that this low value may cause the maximal uncontrolled respiration normally observed in the midgut. The kinetics to anoxia of active transport (Isc) and the redox level of the mitochondrial cytochromes were measured simultaneously in the midgut. The cytochromes became reduced with a time constant of 0.75 +/- 0.15 min, whereas that for Isc inhibition was 2.1 +/- 0.15 min after a delay of 0.25 min. The difference between these two kinetic rates indicates that an intermediate form of energy exists in this tissue to energize active K transport. Measurements of ATP levels during the transition to anoxia indicate that its decay kinetics are sufficiently slow for ATP to be the immediate energy source for active transport in this tissue.

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