Impaired adenylate cyclase activity of phenylhydrazine-induced reticulocytes

Effects of adenosine receptor agonists on volume-activated ion transport in pig red cells

Swelling of pig red cells leads to an increase in a chloride-dependent K flux which can be potentiated by cAMP, whereas cell shrinking causes a selective increase in Na movement which is mediated by a Na/H exchanger. We examined the influence of adenosine and adenosine receptor agonists on the volume-sensitive, ouabain-resistant, chloride-dependent K flux, referred to as Rb flux and volume-activated Na/H exchange pathway. It was found that adenosine and adenosine receptor agonists inhibited the Rb flux. N6-cyclohexyl adenosine (CHA) has been found to be the most potent inhibitor with EC50 of approximately 4.5 microM followed by 2-chloroadenosine (Cl-ado) with EC50 of approximately 27 microM and 5'-(N-ethyl)-carboxamido-adenosine (NECA) with EC50 of approximately 185 microM. CHA also inhibits the cAMP-stimulated Rb flux. However, CHA does not alter the basal intracellular cAMP level nor the intracellular cAMP content raised by exogenously added cAMP. In contrast to the adenosine agonist action on the Rb flux, Na/H exchange, which is activated upon cell shrinkage, exhibits a slight stimulation in response to CHA. These findings suggest that the presence of A1 adenosine receptors on the surface of red cells influences the regulation of volume-activated ion transport.

Effect of splenic congestion associated with hemolytic anemia on mortality of rats challenged with Haemophilus influenzae b

The effect of splenic congestion associated with acute hemolytic anemia on susceptibility to bacterial infection was investigated in rats inoculated with Haemophilus influenzae b by intranasal (in) or intravenous (iv) challenge. The rats were made anemic by phenylhydrazine treatment and were challenged with 10(6) (in) or 5 X 10(7) (iv) H influenzae b. Forty-eight hours after in inoculation of bacteria, the number of bacteria in the blood was 10 times greater in the anemic rats with extensive splenic congestion than in controls. After iv inoculation of bacteria, a significantly (P less than 0.001) higher mortality rate was found in the anemic rats with extensive splenic congestion and fewer bacteria were present in the spleens but not the livers, as compared to normal rats. Since phenylhydrazine-induced hemolytic anemia exhibited an extensive congestion in the spleen, higher mortality rate observed in the anemic rats challenged with H influenzae b may result, in part, from decreased intravascular clearance of bacteria by the spleen.