Erythrocyte sodium-lithium countertransport and blood pressure in identical twin pairs discordant for insulin dependent diabetes.
OBJECTIVE
To investigate whether insulin dependent diabetes is responsible for the abnormal behaviour of the carrier in sodium-lithium countertransport and whether the diabetic state is associated with rise in blood pressure.


METHODS
Case-control study.


METHODS
London teaching hospital.


METHODS
44 twin pairs discordant for insulin dependent diabetes living in United Kingdom and 44 healthy control subjects matched for age, sex, and body mass index. None of the twin pairs or the controls had evidence of microalbuminuria.


METHODS
Sodium-lithium countertransport activity in erythrocytes and arterial blood pressure.


RESULTS
The mean (95% confidence interval) sodium-lithium countertransport activity (mmol Li per litre of red blood cells per h) of the diabetic twins (0.291 (0.244 to 0.338)) was similar to that of their non-diabetic cotwins (0.247 (0.204 to 0.290)); both values were significantly higher than that of the controls (0.187 (0.157 to 0.216); p < 0.05). In addition, systolic blood pressure was higher in those twins with diabetes (127 (122 to 133) mm Hg) than in the non-diabetic cotwins (122 (117 to 127) mm Hg; p < 0.01). There were no significant differences in mean diastolic blood pressure between any of the groups studied.


CONCLUSIONS
The raised erythrocyte sodium-lithium countertransport activity in the diabetic twins compared with the controls seems to be inherited rather than a consequence of overt diabetes. The higher systolic blood pressure in diabetic twins than non-diabetic cotwins indicates that insulin dependent diabetes does exert a small influence on systolic blood pressure.
Hardman
T C
TC
Department of Clinical Pharmacology and Therapeutics, Charing Cross and Westminster Medical School, Westminster Hospital, London.
Dubrey
S W
SW
Leslie
D G
DG
Hafiz
M
M
Noble
M I
MI
Lant
A F
AF
D000328:Adult; D000368:Aged; D001794:Blood Pressure; D016022:Case-Control Studies; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000378:metabolism* / Q000503:physiopathology; D004200:Diseases in Twins; D004912:Erythrocytes / Q000378:metabolism*; D005260:Female; D006801:Humans; D008094:Lithium / Q000493:pharmacokinetics*; D008297:Male; D008875:Middle Aged; D012964:Sodium / Q000493:pharmacokinetics*; D014430:Twins, Monozygotic
D008094:Lithium; D012964:Sodium