Uneven Changes In Circulating Blood Cell Counts With Adrenergic Stimulation To The Canine Spleen

Abstract

1. Responses of splenic diameter measured by sonomicrometry to alpha- and beta-adrenoceptor stimulants were estimated together with simultaneously measured systemic arterial and splenic venous concentrations of red blood cells (RBC), white blood cells (WBC) and platelets (PLT) in anaesthetized dogs. 2. Intravenous and intrasplenic arterial injections of adrenaline, noradrenaline and phenylephrine all produced profound decreases in splenic diameter. Increases in systemic arterial concentrations of RBC produced by these stimulants were observed immediately following the splenic contraction and marked increases in splenic venous concentration of RBC. 3. Adrenaline and noradrenaline both caused rapid and transient decreases in WBC release from the spleen and these agonists then, in addition to phenylephrine, caused gradual and small increases in systemic arterial WBC concentrations. The increases in arterial RBC and WBC concentrations were abolished by transient isolation of the spleen from the systemic circulation. These three agents did not significantly modify differences between splenic venous and systemic arterial concentrations of PLT. 4. Intra-arterial injections of isoprenaline caused an increase in splenic diameter and a significant decrease in the splenic venous concentration of WBC, but barely influenced the veno-arterial differences in RBC and PLT concentrations across the spleen. 5. The present results indicate that contraction of the spleen through stimulation of splenic alpha1-adrenoceptors contributes to supplying RBC but not PLT into the systemic circulation, whereas splenic beta-adrenoceptor activation leads to splenic dilatation with increased sequestration of WBC to the spleen despite no changes in the release of RBC and PLT from the spleen.

Responses of the human spleen to exercise

“…Schaffner, Augustiny, Otto, and Fehr (1985) measured spleen size sonographically; the effects of adrenaline on granulocyte counts correlated highly with splenic contraction, but not with spleen size. In dogs, Ojiri et al (2002) reported that the lymphocytic effect of adrenaline was abolished by isolating the spleen from the rest of the circulation. Frey (1914a) further observed that splenectomised rabbits no longer showed a catecholamineinduced lymphocytosis, and the same was true of human participants (Nielsen et al, 1997).…”

Can We Continue Research in Splenectomized Dogs? <i>Mycoplasma haemocanis:</i> Old Problem – New Insight

“…However, investigators are still confronted with considerable variability in the canine cardiovascular shock response, since the canine spleen acts as a blood reservoir and contracts during hemorrhage, expelling red cells, thus increasing hematocrit, circulating blood volume, left ventricular preload, cardiac output and arterial O 2 content [5][6][7], which dramatically enhances the canine cardiovascular stress response [6,8]. Canine splenic contraction is mediated by endothelin and by norepinephrine via · 1 -adrenoceptors [9].…”

Breath-hold diving as a brain survival response

“…This data suggested that the spleen did not have an important role in regulation of platelet concentration, at least in response to breath-hold stimulation, despite changes in spleen size. Ojiri et al [67] came to the same conclusion by analyzing changes in circulating blood cell counts with adrenergic stimulation of the canine spleen.…”