Regulation of gas exchange and haemolymph pH in the cockroach Nauphoeta cinerea

Matthews, Philip G. D. and White, Craig R. (2011) Regulation of gas exchange and haemolymph pH in the cockroach Nauphoeta cinerea. Journal of Experimental Biology, 214 18: 3062-3073. doi:10.1242/jeb.053991

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Author Matthews, Philip G. D.
White, Craig R.
Title Regulation of gas exchange and haemolymph pH in the cockroach Nauphoeta cinerea
Formatted title
Regulation of gas exchange and haemolymph pH in the cockroach Nauphoeta cinerea
Journal name Journal of Experimental Biology   Check publisher's open access policy
ISSN 0022-0949
Publication date 2011-09-15
Sub-type Article (original research)
DOI 10.1242/jeb.053991
Open Access Status File (Publisher version)
Volume 214
Issue 18
Start page 3062
End page 3073
Total pages 12
Place of publication Cambridge, U.K.
Publisher The Company of Biologists
Collection year 2012
Language eng
Formatted abstract
Ventilatory control of internal CO2 plays an important role in regulating extracellular acid–base balance in terrestrial animals. While this phenomenon is well understood among vertebrates, the role that respiration plays in the acid–base balance of insects is in need of much further study. To measure changes in insect haemolymph pH, we implanted micro pH optodes into the haemocoel of cockroaches (Nauphoeta cinerea). They were then exposed to normoxic, hypoxic, hyperoxic and hypercapnic atmospheres while their haemolymph pH,˙VCO2 and abdominal ventilation frequency were measured simultaneously. Intratracheal O2 levels were also measured in separate experiments. It was found that cockroaches breathing continuously control their ventilation to defend a haemolymph pH of 7.3, except under conditions where hypoxia (<10% O2) induces hyperventilation, or where ambient hypercapnia is in excess of haemolymph (>1% CO2). In contrast, intratracheal O2 levels fluctuated widely, but on average remained above 15% in normoxic (21% O2) atmospheres. Decapitation caused the cockroaches to display discontinuous gas exchange cycles (DGCs). The alternating periods of ventilation and apnoea during DGCs caused haemolymph pH to fluctuate by 0.11 units. Exposure to hypoxia caused haemolymph pH to increase and initiated brief bouts of spiracular opening prior to the active ventilation phase. The spontaneous occurrence of DGCs in decapitated cockroaches indicates that central pattern generators in the thoracic and abdominal ganglia generate the periodic gas exchange pattern in the absence of control from the cephalic ganglion. This pattern continues to maintain gas exchange, but with less precision.
Keyword Gas exchange
Haemolymph pH
Acid-base status
Cyclic CO2 release
Discontinuous respiration
Ventilation rate
Desert locust
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2012 Collection
School of Biological Sciences Publications
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Citation counts: TR Web of Science Citation Count  Cited 18 times in Thomson Reuters Web of Science Article | Citations
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