HISTAMINE-INDUCED MICROVASCULAR LEAKAGE IN PIAL VENULES - DIFFERENCESBETWEEN THE SJL J AND BALB/C INBRED STRAINS OF MICE/

The actions of histamine on pial venule leaky site formation were meas ured intravitally in two inbred strains of mice (BALB/c and SJL/J). Pi al venules were visualized using a cranial window microscopy technique , and microvascular leaky site formation was assessed visually using a fluorescein-dextran indicator. SJL/J mice were found to be sensitive to histamine-induced leakage, whereas the BALB/c strain was refractory . Exposure to pertussis toxin enhanced the sensitivity to histamine in the SJL/J strain, but little effect was observed for BALB/c mice. How ever, the employment of a polymerase chain reaction (PCR) technique fo r the detection of mRNA for histamine H-1 receptor identified receptor -specific message in isolated cerebrovascular endothelium from both st rains of mice. The lack of pial responsiveness in the BALB/c mice rema ins unexplained. Mast cells in the dura mater were found to be more nu merous in SJL/J mice than in BALB/c mice. This observation supports pr evious observations of strain-specific differences in CNS inflammation . The results support the concept that genetically controlled differen ces in vascular sensitivity and localization of CNS-associated mast ce lls may play important roles in the generation of vasogenic edema and inflammation in CNS trauma and disease.