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Biomedical subjects

O Henriksen

Publications and source records attributed to O Henriksen.

At least 199 records · Page 11Linked to original sources
PubMed1984

Sympathetic vasoconstrictor nerve function in alcoholic neuropathy.

The peripheral sympathetic vasomotor nerve function was investigated in 18 male chronic alcoholics admitted for intellectual impairment or polyneuropathy. By means of the local 133Xenon washout technique, the sympathetic veno-arteriolar axon-reflex was studied. This normally is responsible for a 50% decrease in tissue blood flow, when the ankle is lowered 40 cm below heart level in the supine individual. The patients with moderate to severe polyneuropathy, taken as a group, did not differ significantly from the group of patients with no or only mild polyneuropathy, although a lesser response was seen (18% and 48% decrease respectively). However, in three patients with moderate neuropathy, and in one patient with no signs of neuropathy, this veno-arteriolar reflex was absent, indicating dysfunction of the peripheral sympathetic adrenergic nerve fibres. The three patients also showed a lesser degree of arteriolar constriction during 45 degrees passive head-up tilt, although none developed symptoms of orthostatic hypotension. Anhidrosis of the feet was found in only three patients. This study lends support to the view that individual differences in the susceptibility to the deleterious effect of alcohol comprise not only the peripheral sensory and motor nerve fibres, but also the thin pseudomotor and vasomotor nerves.

Adult↗
PubMed1984

Inhibitory effect of pentobarbital anesthesia on venous stasis induced arteriolar vasoconstriction in the dog hindleg.

The effect of close intra-arterial administration of pentobarbital in the concentration of about 2 X 10(-4) mol/l on the venous stasis induced arteriolar constriction in the dog hindleg was studied in 6 neurolept anesthetized dogs. It was found that the blood flows and vascular resistances in the legs before pentobarbital infusion were equal and the vasoconstrictor responses to venous stasis were the same. Pentobarbital infusion into the femoral artery in one of the legs increased the total leg blood flow compared to the control leg and abolished the increase in vascular resistance during venous stasis. In another experimental series the effect of general pentobarbital anesthesia on the vasoconstrictor activity in response to venous stasis locally in subcutaneous and muscle tissue in the hind limb was examined in 6 dogs. It was found that during the first 2-3 h of anesthesia the vasoconstrictor response was present in both tissues although the response in muscle tissue exhibited a great variation between the dogs during this period. However, after 4-5 h of anesthesia the response was abolished in both tissues. During neurolept anesthesia with fentanyl/N2O the same vasoconstrictor response was demonstrated in the hindleg 1 h and 5 h after induction of the anesthesia. It is concluded that pentobarbital anesthesia abolishes the arteriolar constriction induced by venous stasis. The mechanism may be blockade of the local sympathetic vasoconstrictor fibres or interference with myogenic vasoconstrictor mechanism of the vascular smooth muscle cells or both. It is suggested that fentanyl/N2O anesthesia is better suited for this kind of studies.

Anesthesia, General↗
PubMed1983

Impaired autoregulation of blood flow in skeletal muscle and subcutaneous tissue in long-term Type 1 (insulin-dependent) diabetic patients with microangiopathy.

Autoregulation of blood flow was studied in skeletal muscle and subcutaneous tissue in seven Type 1 (insulin-dependent) diabetic patients (median age: 36 years) with nephropathy and retinopathy and in eight normal subjects of the same age. Blood flow was measured by the local 133Xe washout technique. Reduction in arterial perfusion pressure was produced by elevating the limb 20 and 40 cm above heart level. Blood flow remained within 10% of control values when the limb was elevated in normal subjects. In five of the seven diabetic subjects blood flow fell significantly in both tissues when the limb was elevated 40 cm indicating impaired autoregulation. The results suggest that intrinsic vascular (arteriolar) mechanisms (myogenic and/or metabolic) underlying the normal autoregulatory response are defective in some diabetic patients with microangiopathy.

Adult↗
PubMed1983

Local blood flow regulation in normotensive man during prolonged treatment with propranolol.

The influence of propranolol on blood flow in peripheral tissues was studied in 10 normotensive subjects. Adequacy of beta-blockade was ascertained by an ergometric test. Perfusion of the subcutaneous tissue and skeletal muscle was measured by the local 133Xe-washout technique. The arteriolar dilatation underlying the autoregulatory response to a decrease in arterial perfusion pressurehead was not affected by beta-blockade. Propranolol did not change the magnitude of arteriolar constriction elicited by the local sympathetic veno-arteriolar reflex. Thus, the locally induced increase in the discharge rate along the peripheral sympathetic adrenergic fibres did not lead to measurable change in beta-receptor activity. The present results indicate that local bloodflow regulatory mechanisms are not affected by propranolol. They also indicate that the direct peripheral effects of propranolol are of no clinical importance in normotensive subjects in the supine position, when the general activity in the sympathetic nervous system is low.

Adult↗
PubMed1983

Control of skeletal muscle blood flow during postural changes in acute myocardial infarction.

Central and local regulation of skeletal muscle blood flow in the leg was studied in the acute phase of myocardial infarction. Blood flow was measured by the local 133Xe washout technique in the anterior tibial muscle. The vasoconstrictor response to increase in venous transmural pressure was not present on day 1 after coronary occlusion but gradually returned during days 2, 3 and 7. A normal response to decrease in arterial perfusion pressure was observed, suggesting that intrinsic vascular reactions responsible for autoregulation of blood flow were not affected in the acute phase of myocardial infarction. Passive head-up tilt (30 degrees) induced vasoconstriction in skeletal muscle tissue. There were no differences in this response at any time during the course of acute myocardial infarction. The abolition of the vasoconstrictor response to increase in venous transmural pressure on day 1 is most likely due to centrally elicited increase in sympathetic activity as a normal vasoconstrictor response was obtained the following days. Decrease in baroreceptor activity induced by head-up tilt enabled a marked neurogenically mediated vasoconstriction in skeletal muscle tissue which was almost unaffected during the course of myocardial infarction.

Adult↗
PubMed1983

Effect of heel-raising exercise upon collateral resistance in patients with occlusion of the superficial femoral artery.

Invasive blood pressure measurements were performed in the common femoral- and popliteal artery of six limbs with occlusion of the superficial femoral artery during upright exercise (heel raising) and intraarterial alpha-receptor blockade. Femoral blood flow was obtained by an indicator dilution method injecting 131 RISA into the femoral artery and sampling from the popliteal artery. Exercise increased femoral blood flow from an average of 184 (SE +/- 27) cm3 . min-1 at rest to 531 (SE +/- 61) cm3 . min-1 during a 40 degrees head up tilt. Intraarterially induced alpha-receptor blockade caused a further increase in blood flow to 685 (SE +/- 86) cm3 . min-1 during exercise. Changes in collateral arterial resistance was calculated relative to the supine resting value. During exercise a decrease of 24% (SE +/- 13) was observed. After alpha-receptor blockade and exercise collateral resistance decreased by 46% (SE +/- 12). The results indicate that the passive head-up tilt induced a constriction of the collateral arteries which is abolished by heel raising exercise (ie standing on tip toe). It seems, however, that during these circumstances there still remains some alpha-receptor mediated constriction of the collateral arteries which is blocked by intraarterially injected alpha-receptor blocking agents.

Aged↗
PubMed1983

Reduction of the veno-arteriolar reflex induced arteriolar constriction in forearm subcutaneous tissue after surgical repair of aortic coarctation.

Arteriolar constriction in subcutaneous tissue elicited by the local sympathetic veno-arteriolar axon reflex was studied in subcutaneous tissue of forearm and leg in 4 patients before and after correction of aortic coarctation. Before the operation the local axon reflex induced an average increase of 154% in vascular resistance in the "hypertensive" forearm and of 76% in the leg. Following coarctectomy the local axon reflex induced increase in vascular resistance decreased in the forearm within 6 months in all patients. Now average increase in vascular resistance was only 109% 3 months after the operation and 45% 6 months after. Minimal vascular resistance in the papaverine relaxed vascular bed was reduced, whereas no systemic changes were seen in the distensibility of the vascular bed. The results indicate that adaptive vascular changes underlying the augmented arteriolar constriction during lowering as well as the increased "minimal vascular resistance" in the forearm are at least partly reversible following coarctectomy.

Adolescent↗
PubMed1983

Intoxication with sodium valproate. A case report.

Sodium valproate is a relatively new compound in the treatment of epilepsy. A female patient was admitted to the hospital after voluntary intake of 30 g sodium valproate. Her serum concentration was 4925 mumol/l, but the course of the intoxication was mild and the patient was soporous for only 12 hours after intake of the compound. Biochemical data may suggest a slight transitory liver affection.

Adolescent↗
PubMed1983

Vibration sense and sympathetic vasoconstrictor activity in patients with occlusive arterial disease.

The function of sympathetic vasoconstrictor fibres was studied in 18 patients with occlusive arterial disease of the legs and somatic neuropathy, as evidenced as an increased vibration perception threshold. Nine patients suffered from long-term diabetes mellitus. Sympathetic vasoconstrictor function was studied by the capability of the local sympathetic venoarteriolar reflex (Henriksen 1977) elicited by lowering the leg to induce an arteriolar constriction in subcutaneous tissue at the ankle level. Blood flow was measured by the local isotope washout technique. In only five patients with loss of vibration sense, abnormal vasoconstrictor function was found. In three of these patients, the abnormal response most likely could be ascribed to impaired function of the vascular smooth muscle cells. Neither in diabetics nor in non-diabetics could an abnormal vibration sense be taken as evidence for loss of sympathetic vasoconstrictor function. It is suggested that this is studied by a simple postural test as used in the present study.

Aged↗
PubMed1983

Changes in subcutaneous blood flow during locally applied negative pressure to the skin.

The effect of locally applied subatmospheric pressure on subcutaneous blood flow was studied in 12 healthy subjects. Blood flow was measured on the forearm by the local 133Xe wash-out technique. Air suction between 10 mmHg and 250 mmHg was applied to the skin. Subatmospheric pressure of 20 mmHg caused only a minor increase of estimated vascular resistance of 9 per cent. Increasing the suction to 40 mmHg caused a pronounced vasoconstriction corresponding to an increase in vascular resistance of about 90%. Further increase in local suction beyond 40 mmHg caused no additional increase in vascular resistance. The vasoconstriction induced by local suction was abolished by local nervous blockade induced by lidocaine in low doses which do not affect myogenic activity of the vascular smooth muscle cells. This finding confirms previous studies that the vasoconstriction mainly is due to a local sympathetic veno-arteriolar axon reflex mechanism. The results suggest that the dominant part of the vasoconstriction induced by the local axon reflex occurs when vascular transmural pressure increases from 20 mmHg to 40 mmHg.

Adult↗
PubMed1983

Effect of chronic sympathetic denervation upon the transcapillary filtration rate induced by venous stasis.

The effect of venous pressure elevation upon capillary filtration rate in the limb was studied in 6 chronically sympathectomized patients. Five healthy subjects served as controls. Volume changes of the forearm or calf were recorded by a strain-gauge plethysmograph. Relative blood flow in subcutaneous and muscle tissue during venous stasis was measured by the local 133Xe washout technique. In the denervated limbs there was a linear relationship between net capillary filtration rate and venous pressure elevation. In the controls a non-linear relationship was seen as venous pressure elevation of 40 mmHg only caused an increase in net filtration rate of about 66% of that expected from a linear relationship. In the denervated limbs of blood flow in muscle and subcutaneous tissue remained constant during venous pressure elevation of more than 30 mmHg whereas in the non-denervated limbs blood flow decreased by about 50% in both tissues. The results suggest that a local sympathetic veno-arteriolar (axon) reflex plays a dominant role for the reduced increase in net capillary filtration during large increases in venous pressure. The local axon reflex may therefore act as an edema protecting factor.

Adult↗
PubMed1983

Contribution of local blood flow regulation mechanisms to the maintenance of arterial pressure in upright position during epidural blockade.

The contribution of local blood flow regulation mechanisms to the maintenance of arterial pressure in upright position was studied in 5 normal subjects. Central sympathetic blockade was induced by epidural anesthesia. Blood flow in anterior tibial muscle in both legs and in brachioradial muscle in one arm was measured by the local 133Xe washout technique. Arterial blood pressure was recorded directly from the radial artery. Slow head-up tilt (about 30 degrees) caused a decrease in blood flow of about 36% in the dependent legs and in arm remaining at heart level. Arterial pressure decreased by about 10%. Blockade of the local sympathetic veno-arteriolar "axon reflex" in one leg by injection of phentolamine into the common femoral artery caused a vasodilatation in the ipsilateral muscle, while muscle blood flow did not change in the other leg or arm. Within 20 s after the injection of phentolamine arterial pressure decreased by about 7%. This cannot be explained by a "systemic" effect because injection of phentolamine into the femoral vein did not effect arterial pressure within the first 40 s. Vasoconstriction due to blood-borne factors is ruled out since preventing the increase in vascular transmural pressure in the leg by inducing counterpressure locally, abolished the vasoconstriction. Thus, the results suggest that the local veno-arteriolar "axon reflex" together with myogenic mechanisms contribute to the maintenance of arterial pressure in the upright position.

Adrenergic alpha-Antagonists↗
PubMed1983

Evidence for a local sympathetic venoarteriolar "reflex" in the dog hindleg.

The study was performed in order to determine whether a local sympathetic venoarteriolar "reflex" is present in the dog hindleg. Femoral artery blood flow was measured by an electromagnetic flowmeter probe, and blood flow in the thigh muscle and subcutaneous tissue distally in the paw was measured by the local 133Xe washout technique. Twenty experiments were carried out in seven dogs unilaterally sympathectomized 2-4 weeks previously. Resting vascular tone did not differ in the sympathectomized and nonsympathectomized legs. In the control leg, venous pressure elevation caused a decrease in femoral blood flow of 49% corresponding to an increase in vascular resistance of 58%. In muscle and subcutaneous tissue vascular resistance increased by 81% and 35%, respectively. In the denervated leg, venous stasis caused no change in total vascular resistance. In muscle the vascular resistance increased by only 24%. In subcutaneous tissue, vascular resistance decreased by 12%. The effect of acute lumbar sympathectomy was studied in another group of seven dogs. Operation caused an immediate decrease in vascular resistance of 40%. The increase in vascular resistance during venous stasis in the total leg, as well as in muscle and subcutaneous tissue, was not affected. However, acute lumbar sympathectomy combined with injection of phenoxybenzamine into the femoral artery almost abolished the vasoconstriction induced by venous stasis. In muscle, the increase in vascular resistance was still present, but considerably attenuated. In subcutaneous tissue, the normal response was completely blocked. Finally, local suction induced vasoconstriction in an adjoining area not subjected to changes in vascular transmural pressure, an effect that could be blocked by local neural blockade at the site of suction. The results strongly suggest that a local sympathetic veno-arteriolar (axon) "reflex" is present in muscle and subcutaneous tissue in the dog hindleg.

Animals↗
PubMed1983

The reflex sympathetic dystrophy syndrome. An experimental study of sympathetic reflex control of subcutaneous blood flow in the hand.

Adrenergic sympathetic vasoconstrictor activity in subcutaneous tissue on the back of the hand was studied in 13 patients suffering from reflex sympathetic dystrophy syndrome. Subcutaneous blood flow was measured by the local 133Xe wash-out technique with simultaneous measurements on the healthy side as a control. The results indicated an increased subcutaneous blood flow in the affected hand compared with the control side. Proximal nervous blockade caused only a slight, 35% increase in subcutaneous blood flow on the affected side, whereas an increase of 122% was registered on the control side. Augmented sympathetic vasoconstrictor activity elicited by the local veno-arteriolar axon reflex mechanism or centrally elicited by head-up tilt caused an equal degree of arteriolar vasoconstriction in both hands. The results suggest that sympathetic vasomotor tone during resting conditions is reduced in the affected hand in patients with the reflex sympathetic dystrophy syndrome.

Aged↗
PubMed1982

Sympathetic reflex control of subcutaneous blood flow in tetraplegic man during postural changes.

1. The effect of head-up tilt upon subcutaneous blood flow in the distal arm and leg was studied in 12 patients with complete traumatic spinal cord transection at the cervical level. 2. Blood flow was measured by the local 133Xe washout technique. 3. Leg lowering induced a 47% decrease in blood flow in the distal leg. During head-up tilt (45 degrees) blood flow in the leg decreased by 48%. In the arm remaining at heart level blood flow decreased by 37% during tilt and this vasoconstriction could be prevented by nervous blockade with lignocaine injected subcutaneously 5 cm proximally to the labelled area. Leg blood flow was unaltered by proximal blockade but could be blocked by local infiltration in the labelled area with lignocaine in low doses. 4. Head-up tilt of tetraplegic patients induced vasoconstriction in the subcutaneous tissue of the forearm, which could be prevented by proximal blockade. Thus the vasoconstriction could be due to a spinal sympathetic reflex mechanism. This as well as local mechanisms including the venoarteriolar reflex may play a role in recovery of arterial blood pressure during head-up tilt in the tetraplegic patient.

Adult↗
PubMed1982

Mechanism of the tilt induced increase in collateral arterial resistance in patients with occlusion of the superficial femoral artery.

Resistance in collateral arteries bypassing an occlusion of the superficial femoral artery was studied in five patients before and during epidural blockade. The patients were placed on a tilt table and the measurements were performed with the patients both in supine and tilted position (40 degrees head up). Arterial blood pressure was measured directly in the brachial, common femoral and popliteal artery. Relative and absolute blood flows were calculated as the relative change in arteriovenous oxygen difference and by an indicator dilution technique. Tilting caused a decrease in relative leg blood flow of 28%. The relative pressure gradient between the femoral and popliteal artery did not change significantly. Calculated relative collateral resistance increased by 49%. During epidural blockade blood flow increased by 39% in supine position corresponding to a decrease in collateral resistance of 22%. During blockade tilting caused a decrease in relative blood flow of 22% compared with the value in supine position. The relative pressure gradient over the occluded superficial femoral artery decreased by 14%. The corresponding calculated relative collateral resistance increased by 14%. The results indicate that the tilt induced constriction of the collateral arteries is mainly neurogenically mediated via the lumbar sympathetic chain, whereas local mechanisms only seems to play a minor role.

Adult↗