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N Heisler

Publications and source records attributed to N Heisler.

11 recordsLinked to original sources
PubMed1979

Acid-base balance of pleural liquid in dogs.

Acid-base balance and electrolyte concentrations were measured in dogs on small artificial hydrothoraces and in vitro on bicarbonate buffered Ringer solution on serosal and interstitial side of specimens of parietal pleura. Under steady conditions, pleural liquid PCO 2 was similar to and pH higher (delta = 0.022 +/- 0.006 SE) than that in mixed venous blood. Computed pleural liquid [HCO-3] was similar to that in venous plasma and hence less than that set by the Donnan effect, with which Na+ and Cl- approximately complied. In vitro, pH, [Na+], [Cl-], and computed [HCO-3] were significantly lower (delta = 0.030 +/- 0.004; -2.6 +/- 0.5; -1.2 +/- 0.5 and -1.7 +/- 0.2 meq/L, respectively) on the serosal than on interstitial side of pleural specimens, PCO2 being 42 mm Hg on both sides . HCO-3 and Na+ were not distributed according to transpleural potential (-0.4 +/- 0.1 mV on serosal side), suggesting an active transport of Na+ and HCO-3 from pleural liquid to blood. This, however, does not seem to add to the absorption pressure of plasma proteins in setting pleural liquid pressure.

Acid-Base Equilibrium↗
PubMed1979

Intracellular pH regulation of normal and hypertrophic rat myocardium.

The myocardial cell pH (pHi) observed during breathing of 0, 7.5, or 10% CO2 in air for 3 h was studied in rats with myocardial hypertrophy due to aortic stenosis and in sham-operated rats. The change in pHi during hypercapnia was significantly smaller in the rats with myocardial hypertrophy, with the apparent nonbicarbonate buffer value (delta [HCO3-]i/delta pHi) being almost three times that of the sham-operated rats. In vitro CO2 equilibrium of myocardial tissue homogenates showed no difference in nonbicarbonate buffer value between homogenates obtained from normal rats and from rats with myocardial hypertrophy. Therefore, it appears that the increased ability of the myocardial cell to regulate its pH during hypertrophy is not due to an increase in the cellular level of nonbicarbonate buffers, but seems to be related to a larger bicarbonate uptake by the myocardial cell during hypercapnia.

Acid-Base Equilibrium↗
PubMed1978

Bicarbonate exchange between body compartments after changes of temperature in the larger spotted dogfish (Soyliorhinus stellaris).

Intracellular/extracellular and extracellular/sea-water bicarbonate exchanges were measured in Larger Spotted Dogfish (Sycliorhinus stellaris) exposed to 10 degrees C temperature step changes in a closed sea-water recirculation system. Changes of the bicarbonate concentration in blood plasma (= extracellular space) and in the recirculating sea-water were monitored for 36 h after the temperature change. Intracellular/extracellular transfer of bicarbonate was computed from bicarbonate changes in the extracellular space and sea-water. When the temperature was changed from 10 to 20 degrees C a signigicant transfer of bicarbonate was observed from the intracellular to the extracellular compartment and from the extracellular compartment to the sea-water. These transfers were reversed when the temperature was lowered from 20 to 10 degrees C. The exchange processes were practically completed after 18 h. The amount of bicarbonate exchanged between intracellular and extracellular compartments and sea-water was larger than predicted on the basis of in vitro buffer values of white, red and heart muscle, suggesting that additional tissues exchange significant amounts of bicarbonate with the extracellular space. It is concluded that physicochemical buffering is not sufficient to account for the observed adjustment of intracellular and extracellular pH and that bicarbonate exchange between body compartments and environment may be the most important regulatory mechamism, responsible for the final adjustment of acid-base balance in dogfish.

Acid-Base Equilibrium↗
PubMed1978

Comparison of efflux rates of hydrogen and lactate ions from isolated muscles in vitro.

Relative rates of efflux of hydrogen and lactate ions from skeletal muscle in vitro were determined on isolated rat diaphragms and frog satorius muscles. After a period of lacate accumulation by stimulation in vitro, muscles were suspended in a small volume of Ringer solution for different time periods lasting up to 60 min. The pH change in the solution was monitored continuously. After the predetermined time period, samples of the muscle and the Ringer solution were analysed for lactate content. Results showed that in both types of muscles the rate of efflux of hydrogen ions exceeded that of lactate ions by factors of about 14 and 50 in the case of diaphragm and sartorius muscles respectively. Because of this difference observed in the efflux kinetics of hydrogen and lactate ions, it is evident that the lactate content of a body compartment does not represent the absolute hydrogen ion load of the same compartment, particularly during the early phase of the efflux process.

Animals↗
PubMed1978

Blood flow distribution in the duck lung and its control by respiratory gases.

Blood flow to subunits of the lung was studied in the duck by use of radioactive microspheres. In spontaneously breathing, unanesthetized animals (series I) neopulmo was slightly better perfused than the average lung and along the paleopulmonic parabronchi, blood flow was found to decrease in the direction of ventilatory gas flow and thus of decreasing PO2 and increasing PCO2 in lung gas. The effects of respiratory gases on regional lung perfusion were investigated in unidirectionally ventilated animals (series II) in which gas mixtures offered to both lungs could be controlled independently. Local hypoxia resulted in reduction of local blood flow, whereas effects from hyperoxia or CO2 could not be substantiated. Reversal of the direction of unidirectional ventilatory flow (series III), and thus reversal of the profiles of respired gas concentrations along the parabronchi, suggest that the inhomogeneity in blood flow observed in spontaneously breathing animals of series I can only in part be explained as an acute adjustment to the local hypoxia. Calculations show that this inhomogeneity of blood flow constitutes an only minor impairment of the overall gas exchange efficacy of the parabronchial lung.

Animals↗
PubMed1977

Estimation of shunting, systemic and pulmonary output of the heart, and regional blood flow distribution in unanaesthetized lizards (Varanus exanthematicus) by injection of radioactively labelled microspheres.

Circulatory parameters in a lizard (Varanus exanthematicus) were determined using the microsphere method. Microspheres (MS) (slightly larger than the erythrocytes and labelled with different gamma-emitting isotopes) were injected into a pulmonary vein or the left atrium for determination of the left-to-right (L-R) shunt and the regional distribution of the ventricular systemic output. Injections were also made into the sinus venosus for determination of the right-to-left (R-L) shunt. The relative blood flow was obtained as the ratio of the MS activity found in the various tissues over the total activity injected. Absolute calibration of the method was performed by introduction of an 'artificial organ' into the circulatory system (Hales, 1973). Ventricular systemic output (VSO), in five animals, averaged 121 ml/ (min.kg) and ventricular pulmonary output 119 ml/(min. kg). The value of VSO was significantly higher than those observed in other lizard species. In all experimental animals both R-L as well as L-R shunting of various extent occurred. The reliability of the microsphere method as applied in lizards is discussed and is considered to be relatively accurate even under conditions of incomplete mixing of shunted and unshunted blood in systemic heart output.

Animals↗
PubMed1976

Extracellular and intracellular pH with changes of temperature in the dogfish Scyliorhinus stellaris.

Larger Spotted Dogfish, Scyliorhinus stellaris, were exposed to varied ambient temperature (t) in order to determine the behavior of extracellular pH (pHe), Pco2 and bicarbonate concentration as well as intracellular pH (pHi) in three muscle types. pHe was found to vary with temperature slightly less than expected on the basis of the rule of constant relative alkalinity in juvenile (deltapH/deltat= -0.0148 per degree centigrade) as well as in adult (deltapH/deltat= -0.0136) fish. The absolute pHe values of adult fish were about 0.08 pH units higher than in juvenile fish. Arterial pco2 increased with rising temperature, the increase being much more marked in adult than in juvenile fish. Extracellular bicarbonate concentration (calculated from the pH and Pco2 values measured in arterial blood) was not maintained constant, but diminished in juvenile and increased in adult fish with increasing temperature, indicating that extracellular pH in dogfish is regulated by variations of both Pco2 and bicarbonate concentration. Variations of intracellular pH with temperature (deltapHi/deltat), -0.0178 for white muscle, -0.0334 for red muscle, and -0.0098 for heart muscle, were significantly different from the values of the extracellular compartment and, except for white muscle, significantly different from the condition for constant relative alkalinity (deltapH/deltat= -0.0183). These results are in agreement with the rule of constant relative alkalinity with respect to extracellular pH and possibly also with respect to an overall mean intracellular pH, but the rule is not quantitatively followed by the individual body compartments and tissues.

Acid-Base Equilibrium↗
PubMed1976

Ventilatory response to hypercapnia in the larger spotted dogfish Scyliorhinus stellaris.

Dogfish were exposed to sudden changes of Pco2 in inspired seawater. During hypercapnia breathing frequency remained constant, but gill ventilation was transiently increased to about 140% of control levels in the 1st h. O2 uptake was significantly increased also, but returned to the initial level before nomalization of gill ventilation. In contrast to the transient rise in gill ventilation and O2 uptake, arterial Po2 was increased for the whole period of hypercapnia. Hypercapnia results in a marked fall in pHa which returned to the initial value in 4-5 h even though hypercapnia is maintained. This rise in pHa with little change in PaCO2 was associated with an increase in plasma bicarbonate concentration. The increase of plasma bicarbonate was in part due to compensatory bicarbonate uptake from the seawater across the gills and in part was effected by transfer between intracellular tissue compartments and extracellular spaces. The compensatory bicarbonate exchange mechanism in the gills seems to have a delay both after onset and termination of hypercapnia.

Acid-Base Equilibrium↗
PubMed1975

Intracellular pH of isolated rat diaphragm muscle with metabolic and respiratory changes of extracellular pH.

Relationships between intracellular and extracellular pH isolated rat diaphragms were determined both during respiratory and metabolic changes of extracellular pH. Metabolic changes of extracellular pH were produced by varying bicarbonate concentration of the suspending Krebs-Ringer solution and respiratory changes were produced by varying PCO2 of the suspending medium. At any defined extracellular pH, the bicarbonate concentration ratios between intracellular and extracellular space were the same during both metabolic and respiratory changes of extracellular pH. However, when extracellular pH varied within 7.15 and 7.4 intracellular pH remained essentially constant. In order to maintain the intracellular pH constant during extracellular pH changes, a bicarbonate efflux during metabolic changes from the intracellular compartment, and a bicarbonate influx during respiratory changes to the intracellular compartment must occur. The maintenance of identical intracellular/extracellular bicarbonate concentration ratios regardless of the mechanisms of extracellular pH changes (metabolic or respiratory) suggests an active mechanism for the transport of bicarbonate or H-+ ions.

Acid-Base Equilibrium↗
PubMedDate not supplied

Hypercapnia and resultant bicarbonate transfer processes in an elasmobranch fish (Scyliorhinus stellaris).

In order to test the effects of hypercapnia on the acid-base status of fish, larger spotted dogfish were exposed to sudden changes of PCO2 in a closed seawater recirculation system. pH, PCO2 and PO2 were determined in arterial blood and seawater. The exchange of bicarbonate between extracellular space (ECS), intracellular space (ICS), and seawater (SW) was obtained from changes of the total bicarbonate amount in ECS and SW. After fourfold increase of PCO2 arterial pH fell markedly, but started to recover immediately towards control values. This was caused by compensatory accumulation of bicarbonate in the ECS. According to the origin of the extracellular bicarbonate increase three periods could be distinguished: 1.-- Bicarbonate transferred from ICS to both ECS and SW; 2. -- Bicarbonate transferred from both SW and ICS to ECS; 3. -- Bicarbonate transferred from SW to both ECS and ICS. After return to normocapnia similar periods occurred with opposite transfer directions and delayed period transitions. In the first period the ICS was found to be the only source for compensatory bicarbonate increases and even in the second period the ICS contributed to compensation of the extracellular pH. Thus bicarbonate exchange with the ICS appears to be an important regulatory mechanism diminishing the extracellular pH variations after changes in PCO2, before other compensatory mechanisms are initiated.

Animals↗