Groeihormoon vetstofwisseling en energievoorziening

De laatste jaren is gebleken, dat vrije vetzuren, die in hoeveelheden van enige honderden microequivalenten per liter in circulerend bloed voorkomen, een zeer belangrijke rol spelen bij de energievoorziening van het menselijk lichaam. Bij toestanden, waarin het lichaam in hoofdzaak is aangewezen op verbranding van vet, zoals tijdens hongeren of bij ontregelde diabetes mellitus, is de bloedspiegel van vrije vetzuren verhoogd en treedt acidose op ........ Zie: Samenvatting

The Effects of Different Doses of Dopamine and Domperidone on Increases of Plasma Norepinephrine Induced by Cold Pressor Test in Normal Man

The effect of dopamine 1 and 3 μg/kg/min i.v., of dopamine 1 and 3 μg/kg/min i.v. combined with domperidone 30 mg per os and of placebo infusion on plasma norepinephrine concentration before and during sympathetic stimulation by a cold pressor test was investigated in 10 healthy volunteers (1 female, 9 males, mean age 28, range 19-41). Dopamine 1 μg/kg/min resulted in a blunting of the rise in plasma norepinephrine concentration during the cold pressor test, compared with placebo infusion. The addition of domperidone to dopamine 1 μg/kg/min abolished this effect. Plasma norepinephrine levels during dopamine 3 μg/kg/min infusion, both with and without domperidone, were not different from placebo, but significantly higher compared to dopamine 1 μg/kg/min infusion. Dopamine 1 and 3 μg/kg/min infusion, both with and without domperidone resulted in a blunted increase in blood pressure compared to placebo infusion. Dopamine 1 μg/kg/min infusion resulted in a lower systolic blood pressure during the cold pressor test compared to dopamine 3 μg/kg/min infusion. No significant changes in heart rate occurred during the cold pressor test comparing the different circumstances. We conclude that in healthy volunteers only dopamine 1 μg/kg/min, but not dopamine 3 μg/kg/min, blunts the increase in plasma norepinephrine concentration during a cold pressor test; this effect is abolished by pretreatment with domperidone. We presume that for dopamine 1 μg/kg/min the inhibitory effects of presynaptic DA-2 receptor or α-2 adrenoceptor stimulation on plasma norepinephrine concentration predominate. When dopamine 3 μg/kg/min is infused, the inhibitory effects might be counteracted by uptake-1 inhibition or enhanced synthesis and release of norepinephrine, either directly or indirectly. (Hypertens Res 1995; 18 Suppl. I: S221S224)

Rapid Deterioration of Diabetic Retinopathy During Treatment with Continuous Subcutaneous Insulin Infusion

The effect of continuous subcutaneous insulin infusion (CSII) on diabetic retinopathy was studied in 19 patients with insulin-dependent diabetes mellitus (IDDM). All had diabetes before age 30. Three patients had no retinal abnormalities at the start of the study, 12 had minimal or mild background retinopathy, and 4 had a preproliferative retinopathy. The follow-up period was 12–14 mo. Fundus photography and fluorescein angiography was performed every 2–6 mo. Despite marked improvement of metabolic control, none of the patients with retinopathy showed reversal of the fundal abnormalities. In seven patients with background retinopathy the abnormalities remained unchanged; in five patients a slight worsening was noted. Four patients with moderate-to-severe background retinopathy showed a rapid and severe progression of the fundal abnormalities into a florid proliferative diabetic retinopathy 3–6 mo after initiation of CSII. A higher incidence of hypoglycemic episodes could not be demonstrated in this group. Two of these patients showed a marked reduction in glomerular filtration rate (GFR), 34% and 38%, respectively, during the course of their follow-up. This is compared with a decrease in GFR by only 5.6% for the group as a whole. The four patients with rapidly progressive retinopathy all had long-standing poorly controlled diabetes with preproliferative retinal changes, diabetic neuropathy, and, with the exception of one patient, signs of nephropathy at the start of CSII. The incidence of these features was nil or very low in the remaining 15 patients. This study and similar ones raise the question of whether rapid improvement in glycemic control, after long periods of poor control, could result in rapid deterioration of retinopathy, especially in those with diabetes of long duration or with preproliferative changes