Comparison of two sulfonylureas with high and low myocardial K(ATP) channel affinity on myocardial infarct size and metabolism in a rat model of type 2 diabetes.

AIMS/HYPOTHESIS: Sulfonylureas (SUs) may impair outcome in patients with acute coronary syndrome. Most experimental studies of the myocardial effects of SU treatment are performed in non-diabetic models. We compared the effect of two widely used SUs, glibenclamide (gb) and gliclazide (gc), with high and low myocardial K(ATP) channel affinity, respectively, at therapeutic concentrations on infarct size, left ventricular (LV) function and myocardial glycogen, lactate and alanine content before and after ischaemia/reperfusion (I/R). METHODS: Non-diabetic Wistar and diabetic Goto-Kakizaki rat hearts were investigated in a Langendorff preparation. Gb (0.1 µmol/l) and gc (1.0 µmol/l) were administrated throughout the study. Infarct size was evaluated after 120 min of reperfusion. Myocardial metabolite content was measured before and after ischaemia. RESULTS: Infarct size was smaller in diabetic hearts than in non-diabetic hearts (0.33 ± 0.03 vs 0.51 ± 0.05, p < 0.05). Gb increased infarct size (0.54 ± 0.04 vs 0.33 ± 0.03, p < 0.05) and reduced post-ischaemic LV developed pressure (60 ± 3 vs 76 ± 3 mmHg, p < 0.05) and coronary flow (4.9 ± 0.5 vs 7.1 ± 0.4 ml min(-1) g(-1), p < 0.05) in gb-treated diabetic rats compared with untreated diabetic rats. On comparing gb-treated diabetic rats with untreated diabetic rats, glycogen content was reduced before (9.1 ± 0.6 vs 13.6 ± 1.0 nmol/mg wet weight, p < 0.01) and after ischaemia (0.9 ± 0.2 vs 1.8 ± 0.2 nmol/mg wet weight, p < 0.05), and lactate (4.8 ± 0.4 vs 3.2 ± 0.3 nmol/mg wet weight, p < 0.01) and alanine (1.38 ± 0.12 vs 0.96 ± 0.09 nmol/mg wet weight, p < 0.05) contents were increased during reperfusion. Gc-treatment of diabetic and non-diabetic rats did not affect any of the measured variables. CONCLUSIONS/INTERPRETATIONS: Gb, but not gc, exacerbates I/R injury and deteriorates LV function in diabetic hearts. These effects of gb on diabetic hearts may be due to detrimental effects on myocardial carbohydrate metabolism.

Cardioprotective effect of L-glutamate in obese type 2 diabetic Zucker fatty rats.

1. Because diabetic hearts have an increased threshold for cardioprotection by ischaemic preconditioning (IPC), we hypothesized that protection by L-glutamate during reperfusion is restricted in Type 2 diabetic hearts. Previously, we found that L-glutamate-mediated postischaemic cardioprotection mimics IPC. 2. Rat hearts were studied in a Langendorff preparation perfused with Krebs'-Henseleit solution and subjected to 40 min global no-flow ischaemia, followed by 120 min reperfusion. L-Glutamate (0, 15 and 30 mmol/L) was added to the perfusate during reperfusion of hearts from non-diabetic (Wistar-Kyoto) and diabetic (Zucker diabetic fatty (ZDF)) rats, studied at 16 weeks of age. The infarct size (IS)/area-at-risk (AAR) ratio was the primary end-point. Expression of L-glutamate excitatory amino acid transporter (EAAT) 1 (mitochondrial) and EAAT3 (sarcolemmal) was determined by quantitative polymerase chain reaction and immunoblotting. 3. The ISS/AAR ratio did not differ between control hearts from Wistar-Kyoto and ZDF rats (0.52 ± 0.03 and 0.51 ± 0.04, respectively; P = 0.90). L-Glutamate (15 mmol/L) significantly reduced the IS/AAR ratio in non-diabetic hearts, but not in diabetic hearts, compared with their respective controls. The higher concentration of L-glutamate (30 mmol/L) reduced infarct size in diabetic hearts to the same degree as in non-diabetic hearts (IS/AAR 0.35 ± 0.03 (P = 0.002) and 0.34 ± 0.03 (P = 0.004), respectively). The mitochondrial L-glutamate transporter EAAT1 was downregulated in hearts from ZDF rats at both the mRNA and protein levels (P < 0.0005 and P < 0.0001, respectively). However, there was no change in EAAT3 expression at the protein level. Myocardial L-glutamate content was increased by 43% in diabetic hearts (P < 0.0001). 4. Hearts from obese diabetic rats have an elevated threshold for metabolic postischaemic cardioprotection by L-glutamate. These findings may reflect underlying mechanisms of inherent resistance against additional cardioprotection in the diabetic heart.

Intermittent peripheral tissue ischemia during coronary ischemia reduces myocardial infarction through a KATP-dependent mechanism: first demonstration of remote ischemic perconditioning.

Remote ischemic preconditioning reduces myocardial infarction (MI) in animal models. We tested the hypothesis that the systemic protection thus induced is effective when ischemic preconditioning is administered during ischemia (PerC) and before reperfusion and examined the role of the K(+)-dependent ATP (K(ATP)) channel. Twenty 20-kg pigs were randomized (10 in each group) to 40 min of left anterior descending coronary artery occlusion with 120 min of reperfusion. PerC consisted of four 5-min cycles of lower limb ischemia by tourniquet during left anterior descending coronary artery occlusion. Left ventricular (LV) function was assessed by a conductance catheter and extent of infarction by tetrazolium staining. The extent of MI was significantly reduced by PerC (60.4 +/- 14.3 vs. 38.3 +/- 15.4%, P = 0.004) and associated with improved functional indexes. The increase in the time constant of diastolic relaxation was significantly attenuated by PerC compared with control in ischemia and reperfusion (P = 0.01 and 0.04, respectively). At 120 min of reperfusion, preload-recruitable stroke work declined 38 +/- 6% and 3 +/- 5% in control and PerC, respectively (P = 0.001). The force-frequency relation was significantly depressed at 120 min of reperfusion in both groups, but optimal heart rate was significantly lower in the control group (P = 0.04). There were fewer malignant arrhythmias with PerC during reperfusion (P = 0.02). These protective effects of PerC were abolished by glibenclamide. Intermittent limb ischemia during myocardial ischemia reduces MI, preserves global systolic and diastolic function, and protects against arrhythmia during the reperfusion phase through a K(ATP) channel-dependent mechanism. Understanding this process may have important therapeutic implications for a range of ischemia-reperfusion syndromes.

Ischaemic preconditioning does not protect the heart in obese and lean animal models of type 2 diabetes.

AIMS/HYPOTHESIS: The prevalence of type 2 diabetes mellitus is increasing worldwide with obese diabetic patients constituting the majority of this population. Type 2 diabetes is associated with increased morbidity and mortality after acute myocardial infarction. Previous experimental studies of ischaemia-reperfusion tolerance in diabetes have only been performed in animal models of type 1 diabetes mellitus, yielding conflicting data. The aim of the present study was to characterise and compare the tolerance to ischaemia and effects of ischaemic preconditioning (IPC) in hearts from obese Zucker diabetic fatty (ZDF) and lean Goto-Kakizaki (GK) type 2 diabetic rats, using non-obese Zucker and Wistar rats as respective controls. METHODS: The two rat strains were divided into 8 groups. The ZDF study (n=47) consisted of: Control -IPC, Control +IPC, ZDF -IPC and ZDF +IPC. The GK study (n=38) consisted of: Control -IPC, Control +IPC, GK -IPC and GK +IPC. Hearts, which were studied in a Langendorff preparation perfused with Krebs-Henseleit buffer, were subjected or not to IPC (+IPC, -IPC) before 50 minutes of regional ischaemia and 120 minutes reperfusion. RESULTS: Ischaemic reperfusion injury was smaller in obese (p<0.05) and lean (p<0.05) type 2 diabetic animals than in their respective control animals. IPC reduced ischaemic reperfusion injury during reperfusion in non-diabetic control rats (p<0.01), but failed to protect hearts from both diabetic animal models. Post-ischaemic haemodynamic recovery was impaired in the ZDF rats compared to both control and GK rats (p<0.05). CONCLUSIONS/INTERPRETATION: Ischaemic preconditioning does not protect hearts from obese or lean type 2 diabetic animals. However, the susceptibility of the type 2 diabetic myocardium to ischaemic damage is lower than in non-diabetic hearts. The method described here could be used as a tool to study the pathogenesis of increased cardiovascular morbidity and mortality in type 2 diabetes.

Maternal hyperglycemia improves fetal cardiac function during tachycardia-induced heart failure in pigs.

BACKGROUND: Fetal tachycardia often leads to cardiac failure, which in experimental settings can be prevented by direct fetal glucose-insulin administration. In this study, we hypothesize that similar effects can be obtained indirectly by inducing maternal hyperglycemia. METHODS AND RESULTS: Systolic and diastolic indices (dP/dt(max) and tau) of left ventricular function were measured by use of high-fidelity catheters during 180 minutes of aggressive atrial pacing ( approximately 300 bpm) in 12 preterm porcine fetuses. In 6 fetuses, maternal hyperglycemia (15 mmol/L) was induced for the last 120 minutes of pacing. The remaining fetuses served as controls. Glucose, insulin, and free fatty acid levels were determined, as was fetal myocardial glycogen content. Maternal glucose infusion led to significant fetal hyperglycemia and hyperinsulinemia but did not change the inherently low fetal levels of free fatty acids. There were no differences between groups with regard to dP/dt(max) (1025+/-226 and 1037+/-207 mm Hg, P=NS) and tau (20.6+/-2.0 and 21.4+/-1.6 ms, P=NS) at baseline (100%). During the 180 minutes of pacing, systolic function (dP/dt(max)) and diastolic function (tau) deteriorated more in the control group than in the hyperglycemic group (P<0.001 for both). At 180 minutes, dP/dt(max) was 62+/-18% of baseline in controls and 85+/-11% in hyperglycemic fetuses (P=0.03), and tau was 117+/-12% and 98+/-4%, respectively (P=0.004). CONCLUSIONS: Induced maternal hyperglycemia improves fetal cardiac function during fetal tachycardia and suggests a possible additional therapeutic option to improve the function of the failing fetal heart before or during antiarrhythmic therapy. The findings may be relevant in fetal heart failure in general.

Transient limb ischemia induces remote ischemic preconditioning in vivo.

BACKGROUND: Ischemic preconditioning reduces local tissue injury caused by subsequent ischemia-reperfusion (IR), but may also have a salutary effect on IR injury of tissues remote from those undergoing preconditioning. We tested the hypothesis that limb ischemia induces remote preconditioning, reduces endothelial IR injury in humans, and reduces experimental myocardial infarct size. METHODS AND RESULTS: Endothelial IR injury of the human forearm was induced by 20 minutes of upper limb ischemia (inflation of a blood pressure cuff to 200 mm Hg) followed by reperfusion. Remote preconditioning was induced by three 5-minute cycles of ischemia of the contralateral limb. Venous occlusion plethysmography was used to assess forearm blood flow in response to acetylcholine at baseline and 15 minutes after reperfusion. Experimental myocardial infarction was achieved by 40 minutes of balloon occlusion of the left anterior descending artery in 15-kg pigs. Remote preconditioning was induced by four 5-minute cycles of lower limb ischemia. Triphenyltetrazolium staining was used to assess the extent of myocardial infarction. In the human study, the response to acetylcholine was significantly attenuated in the control group after 15 minutes' reperfusion, but remote preconditioning prevented this reduction. Limb ischemia caused a significant reduction in the extent of myocardial infarction relative to the area at risk compared with control (26+/-9% versus 53+/-8%, P<0.05). CONCLUSION: Remote ischemic preconditioning prevents IR-induced endothelial dysfunction in humans and reduces the extent of myocardial infarction in experimental animals. Transient limb ischemia is a simple preconditioning stimulus with important potential clinical applications.

Induction of steroidogenic enzyme genes by insulin and IGF-I in cultured adult human adrenocortical cells.

Insulin and the insulin-like growth factors (IGFs) have multiple role in gene expression in steroidogenic cells. We investigated the regulation of steroidogenic enzyme gene expression by insulin and IGF-I in primary cultures of human adrenocortical cells from donors of ages 19-77 years. The effects of insulin and IGF-I observed here were independent of age and sex of the donor. After 5 days in serum-containing medium, cultures were exposed to insulin or IGF-I together with cyclic AMP analogs or ACTH in serum-free defined medium. Insulin and IGF-I at physiological concentrations increased mRNA levels for 17 alpha-hydroxylase and type II 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) in the absence of cyclic AMP or ACTH. They had lesser effects on 21-hydroxylase and cholesterol side-chain cleavage enzyme mRNA levels and were3 without effect on 11 beta-hydroxylase mRNA. All steroidogenic enzyme mRNAs were strongly increased by cyclic AMP or ACTH, and this increase was potentiated by insulin or IGF-I. These effects of insulin and IGF-I were accompanied by decreases in the ratio of dehydroepiandrosterone/cortisol synthesized from pregnenolone by the cultures. Induction of steroidogenic enzyme genes in adult human adrenocortical cells by insulin and IGF-I is unlikely to occur by means of a cyclic AMP-dependent mechanism. These data increase the evidence for an important regulation of steroidogenesis by these hormones.

The zona reticularis is the site of biosynthesis of dehydroepiandrosterone and dehydroepiandrosterone sulfate in the adult human adrenal cortex resulting from its low expression of 3 beta-hydroxysteroid dehydrogenase.

Based on indirect evidence, it has often been assumed that the zona reticularis of the adult human adrenal cortex is the source of the adrenal androgens, dehydroepiandrosterone (DHEA) and DHEA sulfate (DHEAS), but direct tests of this concept have been few. Using the techniques of cell culture, Northern blotting, and RIA, we compared the properties of separated adult zonal cells to those of fetal zone cells, a cell type well known to secrete large amounts of DHEA(S) due to its low expression of 3 beta-hydroxysteroid dehydrogenase (3 beta HSD). In nine glands from donors of a wide age range, the zona fasciculata and zona reticularis were separated and dissociated, and the cells were placed in culture. After 5 days, serum was removed by a 24-h period in serum-free defined medium followed by a 24-h exposure to cAMP analogs, with the optional addition of insulin, also in serum-free medium. The separated fasciculata and reticularis cells showed large differences in the DHEA(S)/cortisol (F) production ratios from added pregnenolone precursor, consistent with the synthesis of only F and essentially no DHEA(S) by fasciculata cells and with the synthesis of mostly DHEA(S) with little or no F by both reticularis cells and fetal zone cells. The different patterns of steroidogenesis were accompanied by a much lower level of expression of type II 3 beta HSD in reticularis cells, similar to that in fetal zone cells. In contrast, other genes were similarly regulated in the two adult zones and in the fetal zone by both cAMP and insulin. The levels of messenger ribonucleic acids for 17 alpha-hydroxylase, cholesterol side-chain cleavage enzyme, 21-hydroxylase, and 11 beta-hydroxylase responded to cAMP and insulin in both reticularis cells and fetal zone cells in the same pattern as that previously established in fasciculata cells. The central role of the limited expression of 3 beta HSD in the DHEA(S)-synthesizing property of reticularis cells was established by inhibition of 3 beta HSD in fasciculata cells with trilostane, which caused them to increase their DHEA/F production ratio to a level exceeding even that in fetal zone cells. There did not appear to any age-related changes in gene expression that could account for the large age-related decline in DHEA(S) biosynthesis in humans in either reticularis or fasciculata cells. Thus, the most likely cause of the age-related decline in adrenal androgen biosynthesis is an age-related decline in the number of functional reticularis cells, without a major change in the differentiated properties of the zonal cells as a function of age.

Ovarian hyperstimulation augments adrenal dehydroepiandrosterone sulfate secretion.

OBJECTIVE: To determine if factor(s) secreted by the ovaries during hyperstimulation potentiate basal and ACTH-stimulated adrenal androgen secretion. DESIGN: Retrospective and prospective and prospective clinical study. SETTING: University tertiary care center infertility clinic. PARTICIPANTS: Two hundred thirteen hyperstimulation cycles in endocrinologically normal women were identified from 92 patients with ovulatory infertility, aged 25 to 45 years. Further, seven endocrinologically normal infertile women, aged 22 to 37 years, who were undergoing empiric ovarian hyperstimulation for infertility were identified and studied. INTERVENTIONS: In the previously performed cycles, basal and peak serum DHEAS and cortisol (F) levels were assayed and compared with each other and to the extant E2 levels. Additionally, at the baseline and the peak of ovarian hyperstimulation cycles, a standard ACTH test was performed and serum was assayed for DHEAS, DHEA, and F. MAIN OUTCOME MEASURE: Basal and ACTH-stimulated serum DHEAS, DHEA (prospective part only), and F concentrations. Where applicable, mean peak values were generated and compared between the baseline and the peak of stimulation with or without a correction for intrapatient variability in F secretion. RESULTS: Basal serum DHEAS levels rose with ovarian hyperstimulation independent of F. Post-ACTH mean peak value concentrations rose with ovarian hyperstimulation for DHEAS but not DHEA or F. CONCLUSIONS: Ovarian hyperstimulation potentiates basal and ACTH perturbed adrenal DHEAS secretion. This implies the existence of a humoral ovarian factor(s) that mediate this ovarian-adrenal cross-talk.

Primary malignant melanoma of the cervix and review of the literature.

Primary malignant melanoma of the cervix was diagnosed in a patient presenting with postmenopausal bleeding. A cervical lesion was biopsied, and diagnosis was established by electron microscopy and staining procedures. After failing radiotherapy, the patient was treated with simple hysterectomy and bilateral salpingo-oophorectomy. The cytology, histology, and electron microscopy of this lesion are presented in addition to a clinical discussion.

Laparoscopic removal of 46XY gonads located within the inguinal canals.

Male pseudohermaphrodites require gonadectomy for the prevention of gonadal malignancy. Laparoscopic gonadectomy has been performed in patients with intra-abdominal gonads and can also be performed in patients whose gonads are located within the inguinal canals.