Control of resting ventilation rate in grasshoppers

We examined the effect of extracellular acid-base status and tracheal gas levels on the ventilation rate of resting Romalea guttata and Schistocerca americana grasshoppers. We manipulated haemolymph pH and [HCO3-] within normal physiological ranges using injections of HCl, NaOH, NaHCO3 and NaCl into the haemocoel. In contrast to terrestrial vertebrates, there was no evidence that extracellular acidification increases ventilation rate in grasshoppers. Elevation of haemolymph bicarbonate levels (by NaHCO3 injection) increased ventilation rate, while depression of haemolymph bicarbonate levels (HCl injection) had no effect. Injection of NaHCO3 also increased tracheal PCO2, suggesting that the effect of the NaHCO3 injection might be mediated by a sensitivity of the ventilatory system to tracheal gases. We tested for effects of tracheal gases on ventilation rate by independently manipulating tracheal PCO2 and PO2 using tracheal perfusions. Ventilation rate was positively correlated with tracheal PCO2 and negatively correlated with tracheal PO2. Increasing tracheal PO2 above normal resting levels or decreasing tracheal PCO2 below normal levels decreased ventilation rate. We conclude that quiescent grasshoppers regulate tracheal PCO2 and PO2 by varying ventilation rate and that both PCO2 and PO2 in the trachea stimulate ventilation in normal, resting grasshoppers.

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Roles of gill and red cell carbonic anhydrase in elasmobranch HCO3- and CO2 excretion

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1987.253.3.r450 ◽

1987 ◽

Vol 253 (3) ◽

pp. R450-R458 ◽

Cited By ~ 8

Author(s):

E. R. Swenson ◽

T. H. Maren

Keyword(s):

Carbonic Anhydrase ◽

Respiratory Acidosis ◽

Red Cell ◽

Acid Base ◽

Terrestrial Vertebrates ◽

Carbonic Anhydrase Inhibition ◽

Normal Metabolism ◽

Acid Base Status ◽

Erythrocyte Carbonic Anhydrase ◽

Co2 Elimination

We studied the roles of gill and erythrocyte carbonic anhydrase in normal CO2 transfer (metabolic CO2 elimination) and in HCO3- excretion during metabolic alkalosis in the resting and swimming dogfish shark, Squalus acanthias. Gill carbonic anhydrase was selectively inhibited (greater than 98.5%) by 1 mg/kg benzolamide, which caused no physiologically significant red cell carbonic anhydrase inhibition (approximately 40%). Enzyme in both tissues was inhibited by 30 mg/kg methazolamide (greater than 99%). Both drugs caused equivalent reductions in HCO3- excretion following an infusion of 9 mmol/kg NaHCO3 as measured by the rate of fall in plasma HCO3- and by transfer into seawater. Methazolamide (red cell and gill carbonic anhydrase inhibition) caused a respiratory acidosis in fish with normal acid-base status, whereas benzolamide (gill carbonic anhydrase inhibition) did not. The only effect observed with benzolamide in these fish was a small elevation in plasma HCO3-. These findings, taken together, suggest that red cell carbonic anhydrase is required for normal metabolic CO2 elimination by the gill. Although carbonic anhydrase is located in the respiratory epithelium, it appears to have no quantitative role in transfer of metabolic CO2 to the environment, a pattern similar to all terrestrial vertebrates. However, carbonic anhydrase in the gill is crucial to this organ's function in acid-base regulation, both in the excretion of H+ or HCO3- generated in normal metabolism and in various acid-base disturbances.

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Interaction between temperature and hypoxia in the alligator

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1993.265.6.r1339 ◽

1993 ◽

Vol 265 (6) ◽

pp. R1339-R1343 ◽

Cited By ~ 7

Author(s):

L. G. Branco ◽

H. O. Portner ◽

S. C. Wood

Keyword(s):

Body Temperature ◽

Blood Gases ◽

The Body ◽

Plasma Lactate ◽

Acid Base ◽

Terrestrial Vertebrates ◽

Beneficial Response ◽

Acid Base Status ◽

Induced Changes ◽

Selected Body Temperature

Hypoxia elicits behavioral hypothermia in alligators. Under normoxic conditions, the selected body temperature is 27.8 +/- 1.2 degrees C. However, when inspired O2 is lowered to 4%, selected body temperature decreases to 15.4 +/- 1.0 degrees C. The threshold for the behavioral hypothermia is between 4 and 5% inspired O2, the lowest threshold measured so far in terrestrial vertebrates. This study assessed the physiological significance of the behavioral hypothermia. The body temperature was clamped at 15, 25, and 35 degrees C for measurements of ventilation, blood gases, metabolic rate, plasma lactate, and acid-base status. Hypoxia-induced changes in ventilation, acid-base status, oxygen consumption, and lactate were proportional to body temperature, being pronounced at 35 degrees C, less at 25 degrees C, and absent at 15 degrees C. The correlation between selected body temperature under severe hypoxia and the measured parameters show that behavioral hypothermia is a beneficial response to hypoxia in alligators.

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The effects of walking on heart rate, ventilation rate and acid-base status in the lobster homarus americanus

Journal of Experimental Biology ◽

10.1242/jeb.201.18.2601 ◽

1998 ◽

Vol 201 (18) ◽

pp. 2601-2608 ◽

Cited By ~ 3

Author(s):

RA Rose ◽

JL Wilkens ◽

RL Walker

Keyword(s):

Heart Rate ◽

Walking Speed ◽

Homarus Americanus ◽

Ventilation Rate ◽

The Other ◽

Maximum Heart Rate ◽

Acid Base ◽

Acid Base Status ◽

All Speeds ◽

Ventilation Rates

American lobsters Homarus americanus were exercised on an underwater treadmill at speeds from 1.7 to 8 m min-1 to determine the effects of exercise on heart rate, ventilation rate and acid-base status. Heart and ventilation rates showed almost instantaneous increases at the start of exercise, but the magnitude of the increase was not related to speed. Maximum heart rate was approximately 80-90 beats min-1 and maximum ventilation rate was 175-180 beats min-1 at all speeds tested. Exercise at all speeds caused a decrease in haemolymph pH, with the acidosis after exercise at 8 m min-1 being significantly greater than at the other three speeds. Concomitant with this acidosis was a large increase in partial pressure of carbon dioxide, with the largest increase occurring after exercise at 8 m min-1. The concentration of lactate in the haemolymph increased to similar levels at all speeds of walking. Davenport analysis indicates that the acidosis was predominantly respiratory in nature. Although it was anticipated that heart and ventilation rates would show increases proportional to the speed of exercise, this was not the case. Rather, the responses were fixed regardless of walking speed. The reason for this phenomenon remains unexplained.

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Acid-base and respiratory responses to hypoxia in the grasshopper Schistocerca americana.

Journal of Experimental Biology ◽

10.1242/jeb.201.20.2843 ◽

1998 ◽

Vol 201 (20) ◽

pp. 2843-2855 ◽

Cited By ~ 10

Author(s):

KJ Greenlee ◽

JF Harrison

Keyword(s):

Co2 Emission ◽

Ph Regulation ◽

Progressive Increase ◽

Schistocerca Americana ◽

Acid Base ◽

Intracellular Ph Regulation ◽

Critical Po2 ◽

Acid Base Status ◽

In Trans ◽

Respiratory Responses

How do quiescent insects maintain constant rates of oxygen consumption at ambient PO2 values as low as 2-5 kPa? To address this question, we examined the response of the American locust Schistocerca americana to hypoxia by measuring the effect of decreasing ambient PO2 on haemolymph acid-base status, tracheal PCO2 and CO2 emission. We also tested the effect of hypoxia on convective ventilation using a new optical technique which measured the changes in abdominal volume during ventilation. Hypoxia caused a progressive increase in haemolymph pH and a decrease in haemolymph PCO2. A Davenport analysis suggests that hypoxia is accompanied by a net transfer of base to the haemolymph, perhaps as a result of intracellular pH regulation. Hypoxia caused a progressive increase in convective ventilation which was mostly attributable to a rise in ventilatory frequency. Carbon dioxide conductance ( micromol h-1 kPa-1) across the spiracles increased more than threefold, while conductance between the haemolymph and primary trachea nearly doubled in 2 kPa O2 relative to room air. The rise in trans-spiracular conductance is completely attributable to the elevations in convective ventilation. The rise in tracheal conductance in response to hypoxia may reflect the removal of fluid from the tracheoles described by Wigglesworth. The low critical PO2 of quiescent insects can be attributed (1) to their relatively low resting metabolic rates, (2) to the possession of tracheal systems adapted for the exchange of gases at much higher rates during activity and (3) to the ability of insects to rapidly modulate tracheal conductance.

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Haemolymph acid-base status, tracheal gas levels and the control of post-exercise ventilation rate in grasshoppers

Journal of Experimental Biology ◽

10.1242/jeb.199.2.391 ◽

1996 ◽

Vol 199 (2) ◽

pp. 391-399 ◽

Cited By ~ 5

Author(s):

K Krolikowski ◽

J Harrison

Keyword(s):

Negative Feedback ◽

Ventilation Rate ◽

Gas Composition ◽

Acid Base ◽

Post Exercise ◽

Considerable Heterogeneity ◽

Exercise Ventilation ◽

Acid Base Status ◽

A New Technique ◽

Ventilation Rates

In grasshoppers, ventilation rate increases after jumping, in association with decreases in haemolymph pH and tracheal PO2 and increases in haemolymph and tracheal PCO2. Are these changes in haemolymph acid-base status or tracheal gas composition causally responsible for the increases in post-locomotion ventilation rate? To answer this question, we manipulated haemolymph acid-base status with injections into the haemocoel and independently manipulated tracheal PO2 and PCO2 with tracheal perfusions. Using a new technique, we continuously monitored ventilation rate and ventilatory pressures on virtually unrestrained insects. Changes in haemolymph acid-base status or tracheal PCO2 did not affect post-exercise ventilation rate, clearly demonstrating that the ventilatory stimulus associated with locomotion is not dependent on negative feedback from these variables. Post-exercise ventilation rate varied with tracheal PO2, with the lowest ventilation rates observed at the lowest tracheal PO2 values, a result opposite to that expected if negative feedback from internal PO2 levels were to drive the increase in ventilation rate. Particularly after activity, there was considerable heterogeneity in unperfused animals between tracheal and haemolymph PCO2, and between tracheal PCO2 in the thorax and leg, consistent with unidirectional airflow and a considerable role for diffusion gradients in the gas exchange of grasshoppers.

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To Manage Infantile Hypertrophic Pyloric Stenosis by "Double-Y Pyloromyotomy" is a better Surgical Approach

Journal of Paediatric Surgeons of Bangladesh ◽

10.3329/jpsb.v1i2.19532 ◽

2014 ◽

Vol 1 (2) ◽

pp. 143-147

Author(s):

Md. Ansar Ali ◽

Kaniz Hasina ◽

Shahnoor Islam ◽

Md. Ashraf Ul Huq ◽

Md. Mahbub-Ul Alam ◽

...

Keyword(s):

Weight Gain ◽

Pyloric Stenosis ◽

Hypertrophic Pyloric Stenosis ◽

Treatment Modalities ◽

Infantile Hypertrophic Pyloric Stenosis ◽

Postoperative Vomiting ◽

Acid Base ◽

Feeding Regimes ◽

Acid Base Status ◽

Postoperative Feeding

Background: Different treatment modalities and procedures have been tried for the management of infantile hypertrophic pyloric stenosis. But surgery remains the mainstay for management of IHPS. Ramstedts pyloromyotomy was described almost over a hundred years ago and to date remains the surgical technique of choice. An alternative and better technique is the double-Y pyloromyotomy, which offer better results for management of this common condition.Methods: A prospective comparative interventional study of 40 patients with IHPS was carried out over a period of 2 years from July 2008 to July 2010. The patients were divided into 2 equal groups of 20 patients in each. The study was designed that all patients selected for study were optimized preoperatively regarding to hydration, acid-base status and electrolytes imbalance. All surgeries were performed after obtaining informed consent. Standard preoperative preparation and postoperative feeding regimes were used. The patients were operated on an alternate basis, i.e., one patient by Double-Y Pyloromyotomy(DY) and the next by aRamstedts Pyloromyotomy (RP). Data on patient demographics, operative time, anesthesia complications, postoperative complications including vomiting and weight gain were collected. Patients were followed up for a period of 3 months postoperatively. Statistical assessments were done by using t test.Results: From July 2008 through July 2010, fourty patients were finally analyzed for this study. Any statistical differences were observed in patient population regarding age, sex, weight at presentation, symptoms and clinical condition including electrolytes imbalance and acid-base status were recorded. Significant differences were found in postoperative vomiting and weight gain. Data of post operative vomiting and weight gain in both groups were collected. Vomiting in double-Y(DY) pyloromyotomy group (1.21 ± 0.45days) vs Ramstedts pyloromyotomy (RP) group(3.03 ± 0.37days) p= 0.0001.Weight gain after 1st 10 days DY vs RP is ( 298 ± 57.94 gm vs193±19.8 gm p=0.0014), after 1 month (676.67±149.84 gm vs 466.67 ± 127.71 gm, p=0.0001), after 2months (741.33± 278.74 gm vs 490±80.62 gm, p=0.002) and after 3 months (582±36.01gm vs 453.33±51.64 gm, p=0.0001).No long-term complications were reported and no re-do yloromyotomy was needed.Conclusion: The double-Y pyloromyotomy seems to be a better technique for the surgical management of IHPS. It may offer a better functional outcome in term of postoperative vomiting and weight gain.DOI: http://dx.doi.org/10.3329/jpsb.v1i2.19532

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