The effect of insulin and sulodexide (Vessel Due F) on diabetic foot syndrome: pilot study in elderly patients.

OBJECTIVE: To assess the efficacy of insulin plus sulodexide (a mixture of 80% heparin-like substances and 20% dermatan sulphate) on diabetic ulcers, and its influence on foot skin microcirculation and diabetic neuropathy. RESEARCH DESIGN AND METHODS: Two groups of diabetic patients, suffering from severe neuropathy and ulceration, were randomly assigned to insulin (I) plus sulodexide (S) (n=12) or insulin plus placebo (P) (n=6) therapy, for 10 weeks. Laser Doppler assessment of foot skin flow (LDF), at rest and 30 or 60 s after arterial occlusion, and nerve conduction tests (sensorial evoked and motoric conduction potentials) have been evaluated in both groups. RESULTS: Postischaemic flow was 2.5 times shorter in ulcerated vs. non-ulcerated feet in diabetic patients. A significant increase in flows after 30 and 60 s ischaemia was detected in both groups at the end of therapy (IS group, ulcerated foot, LDF=60 s: from 99.1+/-14.3 to 218.6+/-28.6 PU, P<.001. IP group=from 110.5+/-13.0 to 164.8+/-15.4 PU, P<.05). The length of reactive hyperaemia was higher in IS vs. IP group (IS: from 30.3+/-2.9 to 43.9+/-2.2 s, P<.001; IP: from 28.7+/-3.0 to 33.3+/-3.3 s, ns). Ninety-two percent of ulcers heals in a mean time of 46.4 days (IS group) vs. 83% and 63.0 days, respectively, in IP group. Nerve conduction studies have not demonstrated within- and between-group differences. CONCLUSIONS: Sulodexide and insulin improve the postischaemic skin flow in ulcerated feet, without affecting nerve conduction tests. The effect of sulodexide results additive to insulin; it is clinically relevant, in the view of the possibility of reducing the time needed to completely heal ulcers. The ultimate validation of these preliminary results requires extensive trials.

Role of nitric oxide in the pancreatic vascular and metabolic responses associated with activation of capsaicin-sensitive neurons.

The effects of local periarterial placement of capsaicin upon pancreatic blood flow, oxygen extraction from pancreatic circulation and oxygen consumption by pancreatic tissue were measured in anesthetized dogs. These studies explored also the possible role of endogenous nitric oxide (NO) in the pancreatic vascular and metabolic responses to periarterial capsaicin. In anesthetized dogs, superior pancreatico-doudenal artery blood flow (SPBF) was measured with an ultrasonic blood flowmeter. Microcirculatory pancreatic blood flow (PBF) was measured with laser-Doppler flowmeter. Arteriovenous oxygen difference (AVO2) across the pancreatic circulation was determined spectrophotometrically. Pancreatic oxygen uptake was calculated as the product of AVO2 and SPBF. Capsaicin applied periarterialy induced initial increase in SPBF, PBF and oxygen uptake. The acute capsaicin-induced vascular dilation was followed by steady state response characterized by significant decrease in SPBF, PBF and oxygen uptake. Inhibition of NO synthase by N omega-nitro-L-arginine (L-NNA) induced pancreatic ischemia and hypoxia. After pretreatment with L-NNA the acute capsaicin-induced pancreatic vascular dilation and the increase in pancreatic oxygen uptake were significantly reduced. Above circulatory and metabolic effects of L-NNA were significantly attenuated when administration of L-NNA was combined with L-arginine. The results of these studies indicate that sensory C-fibers at rest and when activated play a role in the control of pancreatic blood flow and tissue oxygenation. These findings support also the hypothesis that NO plays a role in the mediation of pancreatic vasodilatory action of neuropeptides released from sensory C-fibers.

Nitric oxide mediates intestinal hyperaemic responses to intraluminal bile-oleate.

It has long been recognized that intestinal blood flow increases at mealtimes. Mesenteric hyperaemia is also evoked by activation of sensory peptidergic nerves. Our studies explored the possible role of endogenous nitric oxide (NO) in the rat intestinal vasodilator response to luminal instillation of an oleic acid plus bile mixture before and after acute intrajejunal instillation of capsaicin and after chronic pretreatment with capsaicin. In anaesthetized rats we measured jejunal blood flow (BF) with an ultrasonic Doppler flowmeter and systemic arterial pressure (AP) with a pressure transducer. Intestinal perfusion with 80 mM oleic acid in bile increased BF by 98 +/- 12%. Instillation of 4 mg of capsaicin into the jejunal lumen initially increased BF by 42 +/- 9% but was followed by vasoconstriction. Inhibition of NO synthase with 25 mg/kg i.v. N-nitro-L-arginine (L-NNA) decreased BF by 27 +/- 5% and increased AP by 37 +/- 11%. After treatment with L-NNA and after acute and chronic administration of capsaicin, the bile-oleate-induced maximal increases in BF above control levels were 42 +/- 7%, 65 +/- 12%, and 58 +/- 8%, respectively. The observed inhibitory effect of L-NNA on the intestinal hyperaemic response to the bile-oleate mixture was reversed by pretreatment with L-arginine (100 mg/kg i.v.). In capsaicin pretreated rats the subsequent bile-oleate-induced hyperaemia was reduced in magnitude but the inhibitory effects of L-NNA were proportionately the same as in animals not receiving capsaicin. These findings support the hypothesis that NO is involved with bile-oleate-induced mesenteric hyperaemia.

Role of endogenous nitric oxide in the control of gastric acid secretion, blood flow and gastrin release in conscious dogs.

Nitric oxide (NO) was shown to mediate gastric hyperemia following secretory stimulation but its role in the control of gastric secretion has not been clarified. Secretory studies were carried out on conscious dogs with chronic gastric fistula, Heidenhain pouch and esophageal fistula, while changes in gastric blood flow were measured in the mucosa of Heidenhain pouuch by laser Doppler flowmetry. Plasma gastrin was determined by radioimmunoassay. Infusion of NG-nitro-L-arginine (L-NNA) (bolus i.v. injection of 2.5 mg/kg followed by infusion of 0.5 mg/kg/h), a potent inhibitor of nitric oxide synthase, failed to affect basal gastric secretion or plasma gastrin level but suppressed an increase of this secretion induced by sham-feeding, ordinary meat feeding or i.v. infusion of bombesin (0.5 microgram/kg/h), pentagastrin (4 micrograms/kg/h) or histamine (40 micrograms/kg/h). In tests with feeding and bombesin infusion, L-NNA caused a significant and dose-dependent reduction in plasma gastrin levels. The inhibition by L-NNA of gastric acid secretory response to pentagastrin, histamine or feeding was accompanied by a decline in blood flow. Addition of L-arginine (bolus i.v. dose of 50 mg/kg followed by infusion of 5 mg/kg/h) significantly attenuated the L-NNA induced inhibition of gastric secretion and the reduction in plasma gastrin response as well as in the fall of gastric blood flow. We conclude that endogenous nitric oxide affects the gastric secretion and that this effect is mediated, at least in part, by the changes in the gastrin release and gastric blood flow.

Nitric oxide is involved in the mediation of gastric blood flow and tissue oxygenation.

Endogenous nitric oxide which is enzymatically formed by endothelial cells from L-arginine has been implicated in the control of gastrointestinal circulation. Its role in the mediation of gastric tissue oxygenation has not been studied. We investigated the role of NO in the control of gastric blood flow and oxygen uptake. In anesthetized dogs, total gastric blood flow, gastric mucosal blood flow, systemic arterial and portal venous pressures and the arteriovenous oxygen content difference were studied. From these measurements gastric vascular resistance and oxygen consumption were calculated. Administration of NG-nitro-L-arginine (L-NNA) induced gastric tissue ischemia and hypoxia. Both, systemic arterial pressure and gastric vascular resistance were increased. Above hemodynamic and metabolic effects of L-NNA were significantly attenuated when administration of L-NNA was combined with L-arginine. Our findings suggest that endogenous NO is a tonic vasodilator modulating gastric blood flow and oxygen uptake through influence on the gastric microcirculatory structures responsible for vascular resistance and the nutrient circulation.

Nitric oxide in gastroprotection by sucralfate, mild irritant, and nocloprost. Role of mucosal blood flow.

Pretreatment with sucralfate is known to protect gastric mucosa against the damaging effect of strong irritants, and this protection is accompanied by an increase in mucosal blood flow but the mechanisms underlying these effects have not been elucidated. Similar gastroprotective and hyperemic effects can be obtained with exogenous prostaglandins (PG), mild irritants such as dilute ethanol, and by capsaicin. In this study we investigated the role of nitric oxide (NO) in the prevention of ethanol-induced gastric damage and gastric blood flow by sucralfate, mild irritant such as 20% ethanol, capsaicin, and nocloprost, a stable PGE2 analog. Pretreatment with NG-nitro-L-arginine (L-NNA), an inhibitor of NO synthase, enhanced ethanol-induced mucosal damage and reduced dose-dependently the gastroprotective and hyperemic effects of sucralfate, dilute ethanol, and capsaicin. The doses of L-NNA attenuating significantly the protective effects of sucralfate or 20% ethanol were 25-50 mg/kg, while those reducing the protection by capsaicin were 6.2-12.5 mg/kg. The attenuating effect of L-NNA on gastroprotection was reversed by L-arginine but not D-arginine. For comparison, the gastroprotective (but not hyperemic) effect of nocloprost was not affected by the pretreatment with L-NNA and/or arginine. We conclude that sucralfate, mild irritant, and capsaicin activate the NO system that may contribute to their gastroprotective effect through enhancing mucosal circulation but that NO is not essential for the mucosal protection by PGE2 analog.

Microcirculatory and motor effects of endogenous nitric oxide in the rat gut.

The aim of the study was to determine the role of endogenous nitric oxide (NO) as the mediator of intestinal blood flow and motility. Experiments were performed on anesthetized rats. Blood flow in the jejunum was determined by Laser-Doppler flowmeter. Motility was monitored on the basis of changes in intrajejunal pressure. Systemic arterial pressure was also recorded. To investigate the potential role of nitric oxide in the regulation of basal intestinal blood flow and motility the NO synthase inhibitor NG-nitro-L-arginine (L-NNA) was given systemically. Intravenous bolus of L-NNA (15 mg/kg) reduced basal intestinal blood flow and increased both intestinal motility and arterial pressure in the dose-dependent manner. To test the specificity of the NO synthase blockade we administered L-arginine alone or in combination with L-NNA. Pretreatment with L-arginine (100.0 mg/kg i.v.) alone had no major influence but when combined with L-NNA it reversed the intestinal circulatory and motor effects of L-NNA. The results of these studies suggest that endogenous NO exerts a tonic relaxatory influence on the smooth muscle of the intestinal vessels and intestinal wall.

Effects of peptide YY on pancreatic blood flow and oxygen consumption.

Peptide YY (PYY) is a recently discovered polypeptide which has been proposed as physiological inhibitor of pancreatic exocrine secretion. The purpose of this study was to evaluate the effects of exogenous PYY on pancreatic blood flow and oxygen consumption. In anesthetized dogs, the superior pancreatico-duodenal artery blood flow (SPBF), pancreatic microcirculatory blood flow (PBF) and pancreatic oxygen consumption (PVO2) were determined. Control values for SPBF, PVO2 and PBF averaged 43.3 ml/min, 1.8 ml/min, and 57.5 ml/min/100g of tissue, respectively. Following iv injection of PYY at doses of 200 and 400 pmol/kg the values of SPBF decreased by 12 +/- 1% and 22 +/- 2%, respectively. PVO2 was reduced by those doses of PYY by 9 +/- 1 and 17 +/- 3%, respectively. PBF was also reduced by 16 +/- 2 and 34 +/- 2%, respectively after those doses of PYY. Pretreatment with phentolamine reversed the blood flow and PVO2 responses to PYY because SPBF, PVO2 and PBF were significantly increased above the control level. However, after additional pretreatment with propranolol the pancreatic vascular and metabolic responses to PYY were abolished. The above pancreatic responses to PYY were also significantly reduced after acute adrenalectomy. The experimental data indicate that adrenergic pathway is involved in the mechanism of action of PYY on the pancreatic circulation.

Role of tachykinins in the control of pancreatic secretion and circulation.

Tachykinins (TK) are family of peptides including substance P (SP), substance K (SK) and neuromedin K (NK) that have been found in the nerves of the gastrointestinal tract and proposed to act as neurotransmitters to affect the motor, secretory and circulatory functions of the gut, but little is known about their action on the pancreas. In this study three series of tests were carried out to determine the action of SP, SK and NK on pancreatic secretion in conscious dogs and amylase release from the dispersed rat pancreatic acini and to correlate the alterations in pancreatic secretory and circulatory effects of TK in anesthetized dogs. SP, SK and NK infused i.v. in graded doses (0.12-1.0 microgram/kg per h) in conscious dogs stimulated pancreatic protein outputs reaching, respectively, 38% and 23% of the maximal response to CCK (40 pmol/kg per h). HCO3- outputs were also significantly increased but the highest response did not exceed about 5% of secretin (328 pmol/kg per h) maximum. Cholinergic blockade by atropine abolished the pancreatic responses to tachykinins. When added at various concentrations (10(-11)-10(-7) M) to the incubation medium of rat dispersed pancreatic acini, SK, SP and NK increased in concentration-dependent manner the release of amylase from the resting pancreatic acini and augmented the enzyme release induced by CCK-8 and by urecholine. In anesthetized dogs infused with a background dose of secretin (82 pmol/kg per h), addition of SP, SK and NK caused an immediate and dose-dependent increase in the pancreatic blood flow, oxygen consumption and pancreatic secretion accompanied by a dose-dependent decrease in arterial blood pressure. This study shows that TK are potent pancreatic circulatory stimulants and moderate secretagogues both in vivo and in vitro, acting, at least in part, via cholinergic pathway.

Role of nitric oxide and prostaglandins in sucralfate-induced gastroprotection.

We investigated the role of nitric oxide (NO) and prostaglandins (PG) in the prevention by sucralfate of ethanol-induced gastric damage and the decrease of gastric blood flow and compared them with those obtained with nocloprost, a potent locally acting gastroprotective agent. Sucralfate and nocloprost given intragastrically (i.g.) protected dose dependently the gastric mucosa against the damage by absolute ethanol and prevented the decrease in blood flow induced by ethanol. Pretreatment with NG-nitro-L-arginine (L-NNA), an inhibitor of NO synthase decreased dose dependently the protection and the maintenance of blood flow provided by sucralfate but not by nocloprost. This decrease of sucralfate protection was antagonized by L-arginine but not D-arginine. Pretreatment with indomethacin also reversed, in part, the protective and hyperemic effects of sucralfate but the combination of both indomethacin and L-NNA completely abolished these effects. We conclude that sucralfate activates both the NO and PG systems that cooperate in the gastroprotective action of this drug and that NO is not involved in the protection induced by a PGE2 analog.

[The role of eicosanoids in regulation of blood circulation and metabolism in the stomach]. / Rola eikozanoidów w regulacji krazenia krwi i metabolizmu w zoladku.

The study was carried out on anesthetized dogs to determine the role of eicosanoids in regulation of total, and mucosal gastric blood flow and oxygen consumption in the stomach damaged by the instillation of 25% ethanol. The inhibition of prostaglandins generation by indomethacin caused an ischemia and hypoxia in the stomach. It was an evidence for their basal generation and tonic influence on circulation in this organ. OKY--a blocker of thromboxanes synthesis and NDGA--a blocker of 5-lipoxygenase did not alter circulatory and metabolic parameters in the stomach. Above findings indicate, that thromboxanes and leukotrienes are not involved in the physiological modulation of blood vessels activity and oxygen consumption in the stomach. Administration of 25% ethanol on gastric mucosa affected in a rise of total and mucosal blood flow and oxygen consumption. These effects were significantly potentiated by OKY and NDGA and suggesting, that damaged gastric mucosa is able to generate thromboxanes and leukotrienes which cause vasoconstriction. It seems, that endogenous prostaglandins also play an important role, because the gastric hyperemia and the increase in gastric oxygen consumption after alcohol were inhibited by indomethacin.

Contribution of prostanoids to gastric circulatory and metabolic actions of solcoseryl.

Solcoseryl, a deproteinized extract of calf blood has been used in the treatment of peptic ulcer, but the mechanisms responsible for its therapeutic properties remain elusive. The present study was designed to determine the effects of solcoseryl on gastric total (GBF) and mucosal (MBF) blood flow, gastric oxygen consumption (GVO2) and mucosal formation of prostaglandin E2 (PGE2) and leukotriene C4 (LTC4) in anesthetized dogs. Soloseryl given iv or ia into the oxyntic gland area of canine stomach caused a dose-dependent increase in the GBF, MBF and GVO2, PGE2 and LTC4 contents in the ethanol-treated gastric mucosa showed a 5-12 fold increase over the values in the intact mucosa. The generation of LTC4, but not PGE2, was significantly diminished by solcoseryl. Pre-treatment with indomethacin completely prevented the effects of solcoseryl on mucosal PGE2, but not LTC4 levels, and significantly reduced its circulatory and metabolic actions on the stomach. The results of these studies indicate that solcoseryl causes dilatation of gastric arterioles and precapillary sphincters thereby improving mucosal blood flow and oxygen supply. The results also suggest that endogenous prostaglandins serve as mediators of the vascular and possibly metabolic effects of the drug on the stomach. The observed reduction by solcoseryl in gastric biosynthesis of LTC4 during mucosal injury may be an important factor in the gastroprotective and anti-ulcer effects of solcoseryl.

[The role of cholecystokinin in the regulation of intestinal blood circulation and metabolism]. / Rola cholecystokininy w regulacji krazenia krwi i metabolizmu jelita.

These studies were conducted to assess whether cholecystokinin (CCK) play a role in the regulation of intestinal blood flow and metabolic activity. Anesthetized dogs were subjected to laparotomy and implantation of transducers to measured intestinal blood flow (MBF), intestinal oxygen extraction (AVO2) and intraluminal pressure (IP). Intestinal oxygen consumption (VO2) was calculated as the product of the AVO2 and MBF. CCK8 infused intraarterially in doses 12.5, 25, 50, 75 and 100 pmol/kg-h increased significantly MBF by 5, 8, 11, 15 and 19%. IP increased significantly with the last three doses of CCK by 55, 87 and 145%, respectively. Glucose and oleic acid increased MBF by 12 and 37% and VO2 by 26 and 17%, respectively. Pretreatment with a highly selective CCK-receptor antagonist L-364 718 (1 mg/kg i.v.) abolished the vascular and motor responses to exogenous CCK and significantly reduced intestinal hyperemia and increase in VO2 in response to luminal oleic acid but not glucose. These findings indicate that endogenous CCK may play a role in the intestinal hyperemia after fatty meal and that this effect is primarily mediated by the CCK receptors.

Effects of somatostatin on intestinal circulation and oxygen consumption.

The effects of intraarterial administration of somatostatin upon intestinal blood flow, intestinal capillary surface area, oxygen consumption and intestinal motor activity were measured in anesthetized dogs. Blood flow to the segment of distal ileum was measured with an electromagnetic blood flow meter, and arteriovenous oxygen difference (AVO2) was determined spectrophotometrically. Intestinal oxygen consumption was calculated as the product of AVO2 and total blood flow. The clearance of 86Rb was measured to estimate the density of the perfused intestinal capillaries. Changes in blood flow distribution were estimated from the distribution of radiolabelled microspheres. Intestinal motor activity was monitored from changes in intraluminal pressure. Somatostatin induced a dose-related decrease in intestinal blood flow, capillary surface area and intestinal oxygen consumption. A significant increase in intestinal motor activity was also observed. The data of this study indicate that somatostatin acts on smooth muscle of both arterioles and precapillary sphincters and results in a potent vasoconstriction in the intestinal microcirculation.

Effects of leukotriene C4 on pancreatic secretion and circulation in dogs.

In the present study the effects of leukotriene C4 (LTC4) on exocrine pancreatic secretion and pancreatic blood flow were determined. LTC4 given intravenously in various doses ranging from 0.35 to 2.8 nmol.kg-1.h-1 in conscious dogs caused a dose-dependent inhibition of pancreatic HCO-3 and protein responses to exogenous hormones such as secretin, cholecystokinin octapeptide (CCK-8), and bombesin and to endogenous stimulants including meat feeding and duodenal perfusion with oleate. In tests with pancreatic secretion induced by secretin plus CCK, maximal inhibition by LTC4 occurred at a dose of 1.4 nmol.kg-1.h-1 and reached approximately 70% of the control value for HCO-3 output and 45% for protein output. In tests with separate secretin- or CCK-induced secretion, maximal inhibition occurred at a dose of 1.4 nmol.kg-1.h-1 and reached 38 and 66% of the control HCO-3 and protein secretion, respectively. The same dose of LTC4 reduced the postprandial HCO-3 secretion by approximately 80% and protein output by approximately 70%. After administration of indomethacin, the pancreatic secretion declined, but the inhibitory effects of LTC4 remained unchanged. Pancreatic tissue generated two to three times more LTC4 than the gastrointestinal mucosa, and indomethacin caused further increase in this generation, suggesting that LTC4 may contribute to indomethacin-induced pancreatic inhibition. (ABSTRACT TRUNCATED AT 250 WORDS)

Vasoactive and metabolic effects of leukotriene C4 and D4 in the intestine.

The effects of intra-arterial administration of leukotrienes (LT) C4 and D4 upon total intestinal and mucosal blood flow, intestinal oxygen consumption and motor activity were measured in anesthetized dogs. Blood flow to a segment of distal ileum was measured with an electromagnetic blood flow meter, and arteriovenous oxygen difference (AVO2) was determined spectrophotometrically. Oxygen consumption was calculated as the product of AVO2 and total blood flow. Intestinal mucosal blood flow was determined by a local H2-gas clearance technique. Motor activity was monitored on the basis of changes in intraluminal pressure. LTC4 and LTD4 induced a dose-related decrease in total intestinal blood flow, mucosal blood flow and in oxygen consumption, and an increase in intestinal motor activity. Both LT produced a redistribution of blood flow into the muscular compartment of the intestinal circulation. The results of these studies indicate that LTC4 and LTD4 are potent vasoconstrictors in the intestinal microcirculation, and that endogenous LT may contribute to the microvascular changes leading to the intestinal damage.

Effects of substance P on intestinal circulation and oxygen consumption.

The effects of intra-arterial administration of substance P upon intestinal blood flow, oxygen consumption, intestinal motor activity, and distribution of blood flow to the compartments of the gut wall were measured in anesthetized dogs. Blood flow to the segment of distal ileum was measured with an electromagnetic blood flow meter and A-VO2 was measured spectrophotometrically. Oxygen uptake was calculated as the product of A-VO2 and total blood flow. The clearance of 86Rb was measured to estimate the density of the perfused intestinal capillaries. Changes in blood flow distribution were estimated from the distribution of radiolabeled microspheres. Motor activity was monitored from changes in intraluminal pressure. Substance P induced a dose-related increase in intestinal blood flow, oxygen consumption, and intestinal motor activity. A significant increase in 86Rb clearance and increase in blood flow to the muscles was also observed. The results of these studies indicate that substance P relaxes intestinal arterioles and precapillary sphincters thereby inducing intestinal hyperemia and increased oxygen consumption. These changes, at least in part, might be due to the increased intestinal motility with enhanced metabolic demands of the muscularis for oxygen.

Systemic circulatory effects of pentagastrin.

Effects of pentagastrin on systemic circulation were studied in anesthetized cats. Systemic arterial, central venous and portal pressure were monitored with electromanometers and blood flow through the superior mesenteric artery, common carotid artery, femoral artery and ascending aorta were measured with an electromagnetic blood flow meter. Pentagastrin injected intravenously at a doses of 2.0, 4.0 and 8.0 micrograms/kg induced a dose-dependent fall in arterial pressure, heart rate and cardiac output, increased mesenteric blood flow, decreased common carotid artery blood flow, did not change femoral artery blood flow and slightly rose central venous pressure. Atropine blocked observed effects. After repeated injections of the peptide, tachyphylaxis quickly developed. The obtained results indicate that pentagastrin influences general hemodynamics probably via interaction with cholinergic receptors.