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Biomedical subjects

I Carlsson

Publications and source records attributed to I Carlsson.

31 records · Page 2Linked to original sources
PubMed1984

Central and peripheral haemodynamic effects of non-steroidal anti-inflammatory drugs in man.

The haemodynamic effects of non-steroidal anti-inflammatory (NSAI) drugs can be attributed either to their common property of inhibiting the formation of prostaglandins (PG) in the cardiovascular system, or to direct actions on the tone and sensitivity of the resistance vessels in various regions. Indomethacin (IND) is the most frequently studied NSAI drug, in animals and in man. Its cardiovascular effects differ somewhat from those of other NSAI, due to the fact that, besides inhibiting PG formation, IND acts as a direct vasoconstrictor. The stimulatory effect of IND in vascular smooth muscle results in an increased systemic vascular resistance which, although partially compensated by a decreased cardiac output, gives rise to a moderate increase in systemic blood pressure. The vasoconstrictor effect of IND is of particular interest in patients with ischemic heart disease, since it lowers their already decreased coronary flow, and may thereby accentuate the risk of myocardial infarction. Administration of IND also leads to a decreased blood flow in the splanchnic region, the kidneys, and the brain. The cerebral blood flow is lowered by 25-35%; in addition, IND almost entirely erases the hyperemic flow response to hypercapnia. Of other NSAI drugs, at least aspirin and naproxen are completely devoid of such actions on the cerebral circulation. A common vascular effect of all NSAI drugs is a diminution of reactive hyperemia, the local hyperemia that develops in a tissue subjected to a short period of arterial occlusion. Part of this hyperemic response is dependent on an intact vascular PG formation and consequently it is inhibited when PG formation is blocked. In contrast, NSAI drugs do not affect the functional increase in the blood flow in working skeletal muscle.

Adult↗
PubMed1983

Effect of different prostaglandin synthesis inhibitors on post-occlusive blood flow in human forearm.

The vascular relaxation response in the human forearm that follows a short period of arterial occlusion (reactive hyperemia) was investigated with respect to its dependence on an intact PG synthesis. In 10 healthy subjects, five men and five women, forearm blood flow was measured, using venous occlusion plethysmography, in the basal state and during the recovery phase following 5 min of obstructed arterial flow. The subjects were studied at nine different occasions. At six of these they were pre-treated with the highest recommended doses of either of the PG synthesis inhibitors acetyl-salicylic acid, diclofenac, ibuprofen, indomethacin, naproxen or piroxicam; the remaining occasions were controls, performed in the absence of drugs in the beginning, middle, and end of the series. All the drugs significantly decreased the total reactive hyperemia following 5 min of arterial occlusion. Ibuprofen was the most efficient agent, inhibiting the total reactive hyperemia by more than 70%, and naproxen was least active, producing about 35% inhibition. The rest of the drugs diminished the total reactive hyperemia by 55-65%. Basal forearm blood flow was not affected by either of the agents. From these data we conclude that drugs which inhibit PG synthesis in man have in common the capacity to decrease post-occlusive reactive hyperemia. This indicates that an activation of the local release of arachidonic acid, leading to formation of vasodilator PG, is one of the main factors behind the vascular smooth muscle relaxation response to arterial occlusion.

Adolescent↗
PubMed1983

Effect of cigarette smoking on reactive hyperaemia in the human finger.

The effect elicited by cigarette smoking on the reactive hyperaemia that develops following release of arterial occlusion in human skin was investigated, and compared to the corresponding effects elicited by oral administration of indomethacin (an inhibitor of the prostaglandin-forming enzyme cyclo-oxygenase) or nicotine, or by smoking of nicotine-free cigarettes. Finger blood flow was determined in human volunteers, using venous occlusion plethysmography, in the basal state and after 5 min of arterial occlusion. All subjects were studied before and after they had smoked two tobacco cigarettes, two herbal (nicotine-free) cigarettes, or chewed a nicotine chewing gum. The determinations before and after tobacco smoking were repeated after administration of indomethacin. In separate series, the effects of smoking on heart rate and systemic blood pressure were recorded. The basal finger blood flow was significantly (P less than 0.05) diminished following cigarette smoking, by about 35%, and so was the reactive hyperaemia (P less than 0.05), by about 55%. The reactive hyperaemia after administration of indomethacin in combination with cigarette smoking did not differ from that obtained after cigarette smoking alone. The reactive hyperaemia was not affected by oral administration of nicotine, or by smoking of two herbal cigarettes. Cigarette smoking elicited increases in heart rate and systemic blood pressure that were of similar magnitude before and after indomethacin. From these data, we conclude that cigarette smoking elicits an inhibitory effect on the reactive hyperaemia in the human finger. This effect is probably not caused by nicotine, and seems to act via blockade of the vascular relaxation normally medicated by locally formed cyclo-oxygenase products.

Adult↗
PubMed1983

Platelet aggregability in smoking and non-smoking subjects.

The hypothesis was investigated that the arachidonic acid (AA) system has a different impact on platelet function in smoking compared to non-smoking subjects. Arterial blood was sampled from smokers and non-smokers, and platelet-rich plasma (PRP) was prepared. There were no differences in sex and age distribution between the groups. One portion of the PRP was used to determine the lowest amount of AA required to induce platelet aggregation. In other portions the endogenous anti-aggregatory (prostacyclin/PGI2/-like) activity in the blood was determined, after reinforcing it with theophylline. There was no difference between smokers and non-smokers regarding the amount of AA required to induce platelet aggregation. In fresh PRP prepared from blood from non-smoking subjects theophylline (10(-4) M) induced a 12-17% inhibition of the ADP-induced aggregation of platelets, indicating the presence of endogenous subthreshold concentrations of PGI2-like activity in their blood. The corresponding inhibition in fresh PRP prepared from blood from smokers was significantly lower (4-7%), suggesting lower endogenous concentrations of PGI2-like activity in their blood, or alternatively, decreased platelet sensitivity to the action of such activity. From these data we conclude that smokers differ from non-smokers with regard to their platelet function: platelet aggregability in response to AA is unaffected, while the endogenous anti-aggregatory power in the plasma is decreased. These observations may be of significance for the cardiovascular hazards connected with smoking.

Adult↗
PubMed1982

Use of polytetrafluoroethylene grafts in elderly and high-risk patients.

Despite well established methods of vascular surgery, the elderly patient has not been considered a candidate for operation because of a high operative risk and a limited life expectancy. Simplified surgical procedures and the use of new graft material now permit vascular reconstruction with minimal injury to the tissues, little blood loss, and a short operative time. The immediate postoperative mortality after vascular surgery in 68 patients 70 to 88 years of age threatened with immediate amputation was 3%. Seventy-five percent of the limbs were intact 12 months after operation and 55% after 24 months. Thus when amputation of ischemic extremities seems unavoidable, a vascular reconstruction should always be considered even in elderly patients.

Aged↗
PubMed1978

Influence of food on the absorption of acetylsalicylic acid from enteric-coated dosage forms.

The absorption of acetylsalicylic acid (ASA) from two different enteric-coated dosage forms, tablets (Premaspin) and granules (Reumyl), was studied in healthy volunteers under fasting and non-fasting conditions by following the plasma concentration and urine recovery of salicylates after single doses of ASA 1 g. Conventional tablets (Aspirin) were used as the reference. Under fasting conditions the absorption of ASA from the two different enteric-coated preparations was complete. Taken with food the enteric-coated tablets gave much lower plasma concentrations than under fasting conditions, and absorption was not complete in all subjects. In contrast, absorption from the enteric-coated granules was not influenced by the intake of food. It was concluded that enteric-coated granules of ASA permit more reproducible absorption than enteric-coated tablets.

Adult↗