Summary: Ventricular cells from adult rats were isolated enzymatically and used as a model system for determining what factors affect the release of adenosine triphosphate (ATP) from myocardial cells. The enzyme systems used to isolate cells were trypsin:collagenase; hya1uronidase:collagenase and dispase:collagenase. Adenosine triphosphate was released in greater amounts in response to hypoxia from cells freed by each of the enzymatic procedures. This occurred while the intracellular concentration of ATP remained constant. Experiments were then performed to determine whether the conditions that occur during myocardial ischaemia or hypoxia altered the release of ATP. Cells suspended in either oxygenated or anoxic buffer at a pH of 6.8 released a significantly lower amount of ATP than cells suspended in either condition at pH 7.4. To test the possibility that ATP was released from nucleotide-protein-Ca2+ complexes located in the sarcolemma, artificial disruption of these structures was carried out. Incubation of oxygenated cells with the chelating agent, ethyleneglycol-bis (B-aminoethyl ether)-N, N-tetraacetic acid (EGTA), stimulated the release of ATP in a hyperbolic relationship while incubation of anoxic cells with ethylenediamine tetraacetate (EDTA) stimulated the release of ATP in such a way that the pattern of release followed a sigmoid response with maximal amounts of ATP, 995±55 pmol·mg-2 protein, occurring in the presence of 0.1 to 2.0 mmol·litre-2 EDTA. By incubating cells with radioactive EDTA, there was no indication that EDTA entered the cells. No release of ATP above control levels occurred when EDTA was chelated with Ca2+ before being applied to isolated cells. These data suggest that the source of ATP found extracellularly may have been nucleotide-protein-Ca2+ complexes located in the sarcolemma, and further support the role of ATP as a coronary vasodilator during hypoxic conditions.

No description available.

Rats with streptozotocin-induced diabetes exhibit both a reduction in nerve conduction velocity (NCV) and an impaired regenerative response after nerve injury. Nerve blood flow is also reduced in diabetic rats. Vasodilator treatment normalized the deficit in maximum regeneration distance after nerve injury. This strongly suggests a role for endoneurial hypoxia in the impaired regenerative response associated with diabetes. Inhibition of polyol pathway hyperactivity in diabetic rats corrects the deficit in nerve regeneration. Compensation for impaired essential fatty acid metabolism with evening primrose oil treatment had no significant effect on nerve regeneration, but corrected NCV. These findings implicate these two hyperglycemia-related metabolic disturbances in the development of diabetic nerve dysfunction. Levels of oxidative stress are increased in diabetic rats. It was demonstrated that various treatments which act to decrease levels of oxidative stress corrected both the deficit in nerve regeneration and the reduction in NCV found in diabetic rats. It is suggested that an increase in oxidative stress contributes towards nerve dysfunction in diabetes. Feeding non-diabetic rats a 40% galactose diet causes an increase in polyol pathway activity. These animals exhibited similar deficits in nerve regeneration and NCV to those seen in diabetic rats. Anti-oxidant treatment improved both nerve regeneration and NCV in galactose-fed animals. These studies give support to the suggestion that nerve dysfunction due to the diabetes-induced increase in polyol pathway activity involves an increase in levels of oxidative stress. Levels of certain growth factors are reduced in diabetic rats. Treatment of diabetic animals with ciliary neurotrophic factor normalized both nerve regeneration and NCV. Brain-derived neurotropic factor treatment improved nerve regeneration but had no significant effect on NCV.

No description available.

Thirty-four dogs were anesthetized with sodium pentothal i.v. and maintained with i.v. alpha-chloralose. Neuro-muscular blockade was accomplished with gallamine triethiodide (Flaxedil). Respiratory PCO₂ was monitored continuously while artificial ventilation at a rate of 1 5 cpm and appropriate tidal volume was adjusted to maintain expiratory P CO₂ between 38 and 40 mm Hg. Blood gas analysis (P CO₂, PC₂ and pH) allowed maintenance of blood pH between 7.35 and 7.45 by periodic administration of i.v. sodium bicarbonate. Blood volume was maintained with Dextran 75 when necessary. Body temperature was monitored continuously with an esophageal thermister and maintained automatically with heating elements in the operating table. Arterial vascular isolation of the hindlimbs was accomplished by ligating all major branches of the aorta below the renal arteries except the external iliac arteries. The dog's own blood, taken from a cannula in the abdominal aorta just distal to the renal arteries, was perfused at constant flow into cannulae in the external iliac arteries through separate pumps. Each external iliac artery pressure was monitored separately (Fig. 1). A bilateral laminectomy allowed access to the L₅, ₆ and ₇ spinal segments for electrical stimulation of their ventral roots after section of the corresponding dorsal root. In 26 dogs monophasic square wave stimulation (3 to 10V, 3 msec, 8 to 20 Hz) of the ventral root of L₅, L₆ or L₇ induced:1) a decrease in the perfusion pressure (PP) in the ipsilateral hindlimb (-41.8 - 2.7 mm Hg; mean - SE); 2) a decrease in the PP in the contralateral hindlimb (-32.2 - 2.7); 3) a fall in the aortic pressure (-15.6 - 0.7). (Fig.. 3). Similar effects were observed on stimulation of the peripheral stump of the ventral root. The above described vascular effects of ventral root stimulation were resistant to intra-arterial injections of cholinergic and beta-adrenergic blocking agents administered directly into the hindlimb perfusion lines. The effectiveness of the blockades was tested with direct intra-arterial injections of the appropriate agonists. Antihistaminics (diphenhydramine and mepyramine) similarly administered and tested did abolish the response in doses which did not suppress vascular-reactivity to acetylcholine or isoproterenol. These experiments do not provide a clear explanation of the mechanisms responsible for the contralateral vasodilatation or the fall in aortic pressure. The presence of significant anastomotic channels connecting either the two hindlimbs and/or the hindlimbs with the rest of-the body was excluded. Contralateral vasodilatation might perhaps be explained by the presence of nerve fibres crossing the midline in. the fused impar ganglion of the dog. The drop in aortic pressure was not due to the activation of afferent fibres coursing in the ventral roots, nor to the peripheral release of a vasodilator substance since the onset of the phen-omenom was too fast to be explained on these grounds. The possibility exists that the drop in aortic pressure is due to the activation by the stimulated efferent fibres of some afferent nervous pathways carrying inhibitory impulses to the vasomotor centers. The present experiments, however, do not provide data supporting or excluding this hypothesis. The experimental results strongly suggest that the described vasodilatation may be mediated by histamine released directly or indirectly by the activation of fibres coursing into the lower-ventral roots. / Medicine, Faculty of / Cellular and Physiological Sciences, Department of / Graduate

No description available.

Thesis (doctoral)--Katholieke Universiteit te Nijmegen.

No description available.

This research aimed to measure the effect on health outcomes of implementing selected recommendations of the Grampian Joint Drug Formulary in primary care. Antibiotics used in the treatment of uncomplicated lower urinary tract infections (UTIs), ulcer healing agents and peripheral vasodilators were selected for study, thereby reflecting both acute and chronic prescribing. For the UTI study, 12 randomly selected high and low prescribers of trimethoprim, the recommended agent, each agreed to distribute 20 patient questionnaires. Following a period of 18 months and despite repeated contact with the GPs, only 89/480 (19%) questionnaires had been distributed. Patient response was, however, very high with 80 (90%) questionnaires returned. Health outcome measures identified that trimethoprim resulted in no or mild symptoms in 40/45 (91 %) of patients. These findings must be interpreted with caution due to the low level of questionnaire distribution and thus cannot be extrapolated to the total population of patients. In addition, the poor questionnaire distribution did not permit comparison between trimethoprim and non-recommended therapy. One hundred and eighty four patients receiving repeat prescriptions for ulcer healing agents were identified from one general practice. Therapy in 95 patients did not adhere to formulary recommendations. Changes to therapy were considered inappropriate in 11 patients due to factors such as severe depression and a further 8 were deemed unsuitable for participation for non-clinical reasons. The remaining 76 patients were contacted with 19 (25%) refusing to participate. Fifty seven patients were interviewed using the Glasgow Dyspepsia Severity Score and Short Form 36 (SF-36). Changes in health outcomes were measured for 21 patients where a change in therapy had taken place. These results were difficult to interpret due to the diversity of changes recommended and the lack of data relating to those patients not participating. Work involving peripheral vasodilators aimed to determine the effect on health outcomes of cessation of therapy. Forty five patients receiving these agents in 2 practices were identified, although 8 had not requested a prescription in the previous year. Two further patients were excluded from the study due to cancer and old age. The remaining 35 agreed to be interviewed using the Walking Impairment Questionnaire and SF-36. All patients were subsequently instructed to stop therapy for 2 months, although 6 (17%) refused to follow this instruction, one patient was seriously ill thus was excluded and 3 refused to be reinterviewed. Of the remaining 25 patients, no significant differences were observed in the domains studied. Seventeen patients (68%) expressed no desire to restart therapy, generating considerable savings. These results must be interpreted with caution since those not stopping therapy or refusing re-interview are likely to have responded differently to those completing the study. The measurement of health outcomes following formulary implementation deserves further work.

The objective of these experiments was to investigate the effects of various membrane receptor-mediated and receptor-independent vasodilators on the resistance and capacitance vessels of conscious, unrestrained rats by measuring mean arterial pressure (MAP) and mean circulatory filling pressure (MCFP), an index of total body venous tone. ln the first set of experiments the dose-response effects of the directly-acting vasodilators nitroglycerin, sodium nitroprusside and hydralazine were determined in intact rats as well as in rats treated with the ganglionic blocker, hexamethonium. The effects of these drugs were compared with those of the vehicle, normal saline, in control rats. In intact rats, iv infusion of nitroglycerin did not alter MAP while iv infusions of nitroprusside and hydralazine caused dose-dependent decreases in MAP. In intact rats, nitroglycerin and sodium nitroprusside did. not affect MCFP while hydralazine increased MCFP. After treatment with hexamethonium all three drugs decreased MCFP, though the decreases in MCFP caused by hydralazine were not significantly different from the corresponding changes in saline-treated rats. Therefore, sodium nitroprusside and hydralazine but not nitroglycerin were effective arteriolar dilators in intact rats; all three drugs dilated arterioles in ganglionic-blocked rats, ln intact rats, the direct venodilator actions of nitroprusside and nitroglycerin were masked by endogenous sympathetic tone. When sympathetic nerve activity was attenuated, both drugs had venodilatory effects. Hydralazine, on the other hand, hao insignificant venodilatory effects both in the presence and absence of the sympathetic reflexes. In the second set of experiments we determined the dose-response effects of hexamethonium, phentolamine, prazosin and rauwolscine — the latter being non-selective ⍺, ⍺₁-selective, and ⍺₂-selective adrenoceptor antagonists, respectively — in intact rats. Prazosin and rauwolscine were also administered to rats with reflexly increased venous tone induced by the infusion of hydralazine. In intact rats iv infusions of prazosin, phentolamine and rauwolscine all caused dose-dependent decreases in MAP; only rauwolscine reduced MCFP to levels slightly below control. Hexamethonium caused a aecrease in MAP as well as a markea reduction in MCFP. After venous tone was raised by the infusion of hydralazine, both prazosin and rauwolscine dose-dependently decreased MCFP. Therefore, the resistance and capacitance vessels contain both ⍺₁- and ⍺₂-adrenoceptors. in the intact rat, however, the capacitance vessels are somewhat resistant to the effects of postjunctionally acting ⍺-antagonists in contrast to the effects of hexamethonium which acts at the level of the ganglion. / Medicine, Faculty of / Anesthesiology, Pharmacology and Therapeutics, Department of / Graduate