A fast-response pH meter.

SUMMARY1. The effect of electrically induced 'exercise' on the respiratory oscillation of arterial pH was studied in chloralose-anaesthetized dogs with spinal cord transaction at T8/9 (dermatome level T6/7).2. Respiratory oscillations of arterial pH (presumed to be due to oscillations of arterial Pco2) were sensed with a fast-responding electrode in one carotid artery.Breath-by-breath estimates of the maximum rate of change of pH of the downstroke of the pH oscillation (dpH/dtjmax) were obtained by differentiating the pH signal.3. Consistent with the findings of the previous paper (Cross et al. 1982), the ventilatory response to exercise could not be explained on the basis of sensitivity to C02; the A T4/APaco, was significantly greater for 'exercise' than for CO2 inhalation.4. On average, the amplitude of the pH oscillations decreased during 'exercise'.The change in the phase relationship (0) between respiratory and pH cycles, although significant from the second breath onwards, was not thought to be responsible for the increased ventilation V,; the direction of the change was opposite to that previously found to increase VI. 14 and dpH/dtjmax were also linearly related during the on-transient, although the same relationship did not hold true throughout 'exercise'.6. The dpH/dtjmax was related to CO2 production (1rco,) lending support to the prediction that the slope of the downstroke of the pH oscillation is a function of TCo2.7. It was concluded that the dpH/dtimax (dpCO2/dttmax) is a potential humoral signal in 'exercise' and could account totally for the shortening of te. Since there was a late rise in VI (due to an increase in tidal volume VT) in the absence of a change in dpH/dtjmax, it was considered unlikely that the dpH/dtjmax was the only humoral signal present during 'exercise'.

Section: Methodsmentioning

confidence: 99%

The pH oscillations in arterial blood during exercise; a potential signal for the ventilatory response in the dog

Cross¹,

Davey²,

Guz³

et al. 1982

“…The technique for the continuous recording of arterial pH has been described elsewhere (Band & Semple, 1966Cowell, Band & Semple, 1967;Band et al 1969a, b). A glass electrode in the form of a blind-ended capillary fits closely into the lumen of a modified Cournand needle; blood flows in the narrow annular space between the two.…”

Section: Methodsmentioning

confidence: 99%

The effect on respiration of abrupt changes in carotid artery pH and PCO₂ in the cat

Band¹,

Cameron²,

Semple³

1970

SUMMARY1. An in vivo pH monitoring technique was used to assess changes in pH, and by inference changes in PCO., in the carotid artery of anaesthetized cats. The changes in carotid artery pH and respiration following abrupt injections of various acids into the carotid artery or aorta were investigated.2. Injections of saline equilibrated with 100% C02, timed to produce changes at the carotid body chemoreceptors during early inspiration caused an increase in the tidal volume of that breath. The amplitude and rate of change of the pH changes so produced were comparable with those of the oscillations in pH produced by respiration itself.3. The respiratory responses to injection of saline equilibrated with 100 % C02 occurred whether the animal was breathing air or 100 % 02.4. Injections of lactic or hydrochloric acid were without an effect on respiration, except when pH changes larger than 0.1 pH unit were produced. A NaHCO3 solution equilibrated with 30 % C02 stimulated respiration, even though the solution was alkaline to the cat's arterial blood and induced an alkaline change in arterial pH.5. Infiltration of the carotid sinus nerve area with procaine temporarily abolished the respiratory response to injections of saline equilibrated with 100 % C02.

“…The loop had a side arm into which a needle could be inserted containing a fast response pH electrode. This technique for continuous recording of arterial pH has been described elsewhere Cowell, Band & Semple, 1967). The glass electrode fitted closely into the lumen of a short length of needle tubing; blood flowed through a narrow annular space between the electrode and the tubing, through a sidearm on the needle, then through a saturated calomel reference electrode and returned into the femoral vein via the catheter.…”

mentioning

confidence: 99%

Dependence of phrenic motoneurone output on the oscillatory component of arterial blood gas composition.

Cross¹,

Grant²,

Guz³

et al. 1979

Self Cite

SUMMARY1. The hypothesis that respiratory oscillations of arterial blood gas composition influence ventilation has been examined.2. Phrenic motoneurone output recorded in the C5 root of the left phrenic nerve and the respiratory oscillations of arterial pH in the right common carotid artery were measured in vagotomized anaesthetized dogs which had been paralysed and artificially ventilated.3. The effect of a change in tidal volume for one or two breaths on phrenic motoneurone output was measured with the inspiratory pump set at a constant frequency similar to, and in phase with, the animal's own respiratory frequency. A reduction of tidal volume to zero or an increase by 30 % led to a corresponding change of mean carotid artery pH level. The changes of carotid artery pH resulted in a change of phrenic motoneurone output, predominantly of expiratory time (Te) but to a lesser extent of inspiratory time (TI) and also peak amplitude of 'integrated' phrenic motoneurone output (Phr). Denervation of the carotid bifurcation blocked this response.4. The onset of movement of the inspiratory pump was triggered by the onset of phrenic motoneurone output. When a time delay was interposed between them, the phase relationship between respiratory oscillations of arterial pH and phrenic motoneurone output altered. The dominant effect was to alter Te; smaller and less consistent changes of Phr and Ti were observed.5. When the inspiratory pump was maintained at a constant frequency but independent of and slightly different from the animal's own respiratory frequency (as judged by phrenic motoneurone output), the phase relationship between phrenic motoneurone output and the respiratory oscillations of pH changed breath by breath over a sequence of 100-200 breaths, without change of the mean level of arterial blood gas composition. Te varied by up to 30 % about its mean value depending on the phase relationship. Ti and Phr were also dependent on the phase relationship but varied to a lesser extent. The changes were comparable to the results obtained in paragraph 4.6. It was concluded that phrenic motoneurone output is dependent in part on its relationship to the respiratory oscillations of arterial blood gas composition.