Importance of the lactate anion in control of breathing

Hardarson, Thorir, Jon O. Skarphedinsson, and TorarinnSveinsson. Importance of the lactate anion in control ofbreathing. J. Appl. Physiol. 84(2):411-416, 1998.The purpose of this study was to examine theeffects of raising the arterialLa andK⁺ levels on minute ventilation(E) in rats. EitherLa or KCl solutions wereinfused in anesthetized spontaneously breathing Wistar rats to raisethe respective ion arterial concentration ([La] and[K⁺]) gradually tolevels similar to those observed during strenuous exercise.E, blood pressure, and heart rate wererecorded continuously, and arterial[La],[K⁺], pH, and bloodgases were repeatedly measured from blood samples. To prevent changesin pH during the Lainfusions, a solution of sodium lactate and lactic acid was used. Raising [La] to13.2 ± 0.6 (SE) mM induced a 47.0 ± 4.0% increase inE without any concomitant changes ineither pH or PCO₂. Raising[K⁺] to 7.8 ± 0.11 mM resulted in a 20.3 ± 5.28% increase inE without changes in pH. Thus ourresults show that Laitself, apart from lactic acidosis, may be important in increasing E during strenuous exercise, and weconfirm earlier results regarding the role of arterial[K⁺] in the control ofE during exercise.

     

Mature males of Arctic charr,Salvelinus alpinus,release F-type prostaglandins to attract conspecific mature females and stimulate their spawning behaviour

Synopsis We examined the behavioural and biological functions of prostaglandins (PG) of F-type as a chemosensory signal during spawning in Arctic charr. Immunoassay revealed F-type PGs in water inhabited by ripe charr of both sexes performing spawning-related acts. High concentrations of immunoreactive PGFs seemed to coincide with male spawning activity. Ripe isolated males were more odorous to other charr (as assayed by EOG) than either females or immature charr. When these males received chemical cues from ovulated females, they increased their release of odorants, including F-type PGs, into the water. PGF_2α at concentrations of 0.1 nM attracted ovulated females and ripe males. It also stimulated digging behaviour in mature females. It is concluded that F-type PGs or their derivatives are released by ripe males on the spawning grounds to attract females and elicit their spawning behaviour.