Study of alpha adrenoreceptors and plasma catecholamines in insulin-dependent diabetics

ABSTRACT

This study was intended to estimate the number and sensitivity of alpha and beta adrenergic receptors in IDDM patients and to determine their relation to plasma catecholamine levels. Plasma epinephrine, norepinephrine and dopamine levels, as well as platelet alpha-2 adrenoreceptor density and responsiveness, alpha-1 receptor sensitivity, B[2] density and responsiveness and B[1] responsiveness were estimated in 43 insulin dependent diabetics and 56 healthy persons taken as control. Plasma norepinephrine levels were significantly low in diabetics, whereas epinephrine and dopamine levels were normal. Platelet alpha-2 receptor density was significantly high and their responsiveness was markedly low in diabetics. Alpha-1 receptor responsiveness was normal. The elevated alpha-2 receptor density could be directly attributed to the low plasma norepinephrine levels. The reduced alpha-2 receptor responsiveness is most probably due to a post-receptor mechanism. This might be beneficial as it partly counteracts the platelet aggregatory effect of the impaired prostacyclin production by the diabetic capillary cndothclium