Neuronal responsiveness to central Na+ in 2 congenic strains of Dahl salt-sensitive rats.
Dahl salt-sensitive rats show increased Na(+) entry into the brain on high salt intake and increased sympathetic and pressor responses to central Na(+). We examined C10QTL2 and C17QTL to test whether they contribute to these phenotypes. In Dahl salt-sensitive, Lewis, and C10S.L16, and C17S.L2 congenic rats on a high salt diet for 8 to 10 days, blood pressure and heart rate were higher in Dahl salt-sensitive versus others and in C10S.L16 and C17S.L2 versus Lewis rats. Cerebrospinal fluid [Na(+)] increased by approximately 5 mmol/L in Dahl salt-sensitive, C10S.L16, and C17S.L2 compared with Lewis rats. In rats on a regular salt diet, 8-minute intracerebroventricular infusions of artificial cerebrospinal fluid with increasing [Na(+)] caused increases in blood pressure, heart rate, and renal sympathetic nerve activity, which were approximately 90% larger in Dahl salt-sensitive and C17S.L2 versus Lewis rats and only 35% to 45% larger in C10S.L16 versus Lewis rats. In another set of rats on regular salt, blood pressure and heart rate were recorded by telemetry before and during intracerebroventricular infusion of Na(+)-rich cerebrospinal fluid for 14 days. Na(+)-rich cerebrospinal fluid caused significantly larger increases in blood pressure and heart rate, larger responses to air stress and more impairment of baroreflex in Dahl salt-sensitive and C17S.L2 rats versus Lewis rats. In contrast, responses in C10S.L16 rats were similar to those in Lewis rats. These data suggest that, in Dahl salt-sensitive rats, genetic variants in C10QTL2 but not C17QTL contribute to increased neuronal responsiveness to cerebrospinal fluid [Na(+)]. However, neither of them contributes to the increase in cerebrospinal fluid [Na(+)] induced by high salt.
Huang
Bing S
BS
University of Ottawa Heart Institute, Ottawa, Ontario, Canada.
Ahmad
Monir
M
Deng
Alan Y
AY
Leenen
Frans H H
FH
D000818:Animals; D020296:Animals, Congenic; D017704:Baroreflex / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology; D002712:Chlorides / Q000097:blood; D005260:Female; D006339:Heart Rate / Q000187:drug effects* / Q000502:physiology; D006973:Hypertension / Q000134:cerebrospinal fluid / Q000235:genetics; D008297:Male; D010641:Phenotype; D011188:Potassium / Q000097:blood; D051381:Rats; D020303:Rats, Inbred Dahl; D011917:Rats, Inbred Lew; D012964:Sodium / Q000097:blood / Q000134:cerebrospinal fluid*; D012982:Sodium, Dietary / Q000494:pharmacology*; D013564:Sympathetic Nervous System / Q000187:drug effects* / Q000502:physiology
D002712:Chlorides; D012982:Sodium, Dietary; D012964:Sodium; D011188:Potassium