Genetic transmission of hyper-responsivity in crosses between spontaneously hypertensive and Wistar-Kyoto rats.
Cardiovascular and behavioural responses to alerting stimuli (100 ms air puff) are exaggerated in spontaneously hypertensive rats (SHR). Wistar-Kyoto rats (WKY) exhibit bradycardia accompanying a startle-induced pressor response, whereas SHR demonstrate tachycardia. This study was designed to determine whether hyper-responsivity to startle is genetically linked to hypertension in SHR. An F1-generation, bred from SHR males and WKY females, demonstrated motor and cardiovascular responsiveness not different from WKY parents. Brother-sister mating of F1-animals produced an F2-generation with widely distributed blood pressures. Segregation of F2 by systolic blood pressure (greater than 180 or less than 180 mmHg) produced a 1:3 distribution. Neither group showed abnormal motor or pressor responses to startle. However, the F2 group with elevated arterial pressure exhibited tachycardia to startle that was similar to SHR grandparents. The heart rate response to acute stress may therefore serve as a more reliable genetic marker for hypertension than either the behavioural or blood pressure response, and apparently shares close genetic linkage with the hypertension.
Casto
R
R
Department of Pharmacology, University of California, San Diego, La Jolla 92093.
Printz
M P
MP
D000818:Animals; D001794:Blood Pressure; D006339:Heart Rate; D006973:Hypertension / Q000235:genetics*; D051381:Rats; D011918:Rats, Inbred SHR / Q000235:genetics*; D011919:Rats, Inbred Strains / Q000235:genetics*; D011921:Rats, Inbred WKY / Q000235:genetics*; D013216:Reflex, Startle / Q000502:physiology*