Direct assessment and diminished production of morphine stimulated NO by diabetic endothelium from saphenous vein.
Abstract
AIM: To directly measure in real time basal and stimulated levels of NO released
from human saphenous vein endothelium and to quantify the expression of the mu
opiate receptor, which has been linked with NO release.
METHODS: Saphenous vein segments from patients with type 2 diabetes (n=12) and
patients without diabetes (n=8) were obtained. The release of NO was measured
directly from the endothelium using a NO-specific amperometric probe.
N(Omega)-nitro-L-arginine methyl ester (L-NAME, 0.1 mmol/L), a NO synthase (NOS)
inhibitor, or morphine (1 mumol/L), a stimulant, was administered and the
measurements were repeated. Values were reported relative to the mean initial
measurement of NO release from diabetic endothelium, which was defined as the
relative zero level of NO release. A RT-PCR was then performed on the endothelium
to measure mu opiate receptor expression.
RESULTS: Diabetic patients (n=12) showed a relative and significantly diminished
basal level of released NO, (0.049+/-0.012) nmol/L, compared with non diabetic
patients (n=8), (0.42+/-0.12) nmol/L (P<0.05). Application of L-NAME to
nonstimulated tissues resulted in no change in NO release from the diabetic group
and a decrease in NO release of (0.21+/-0.09) nmol/L from the non diabetic group
(P<0.05). Morphine stimulation of the diabetic endothelium resulted in a lower
peak and shorter duration of NO release compared to the non-diabetic tissue,
(21+/-6) nmol/L vs (38+/-4) nmol/L and (7.3+/-1.4) min vs (12.2+/-2.2) min,
respectively (P<0.01). Lastly, evaluation of the mu opiate receptor expression
was found to be diminished in the diabetics by 59.1 %.
CONCLUSION: Maturity-onset diabetes attenuates both the constitutive basal and
morphine stimulated NO release from human saphenous vein endothelium. In this
study, after NOS inhibition, the actual basal NO release in diabetes was
negligible. One explanation for the impaired capacity of diabetic endothelium to
release NO was the diminished mu opiate receptor that was seen in diabetic
endothelium.
Keywords:
from human saphenous vein endothelium and to quantify the expression of the mu
opiate receptor, which has been linked with NO release.
METHODS: Saphenous vein segments from patients with type 2 diabetes (n=12) and
patients without diabetes (n=8) were obtained. The release of NO was measured
directly from the endothelium using a NO-specific amperometric probe.
N(Omega)-nitro-L-arginine methyl ester (L-NAME, 0.1 mmol/L), a NO synthase (NOS)
inhibitor, or morphine (1 mumol/L), a stimulant, was administered and the
measurements were repeated. Values were reported relative to the mean initial
measurement of NO release from diabetic endothelium, which was defined as the
relative zero level of NO release. A RT-PCR was then performed on the endothelium
to measure mu opiate receptor expression.
RESULTS: Diabetic patients (n=12) showed a relative and significantly diminished
basal level of released NO, (0.049+/-0.012) nmol/L, compared with non diabetic
patients (n=8), (0.42+/-0.12) nmol/L (P<0.05). Application of L-NAME to
nonstimulated tissues resulted in no change in NO release from the diabetic group
and a decrease in NO release of (0.21+/-0.09) nmol/L from the non diabetic group
(P<0.05). Morphine stimulation of the diabetic endothelium resulted in a lower
peak and shorter duration of NO release compared to the non-diabetic tissue,
(21+/-6) nmol/L vs (38+/-4) nmol/L and (7.3+/-1.4) min vs (12.2+/-2.2) min,
respectively (P<0.01). Lastly, evaluation of the mu opiate receptor expression
was found to be diminished in the diabetics by 59.1 %.
CONCLUSION: Maturity-onset diabetes attenuates both the constitutive basal and
morphine stimulated NO release from human saphenous vein endothelium. In this
study, after NOS inhibition, the actual basal NO release in diabetes was
negligible. One explanation for the impaired capacity of diabetic endothelium to
release NO was the diminished mu opiate receptor that was seen in diabetic
endothelium.