Vasoactive alterations in lower limb subcutaneous resistive arteries from Caribbean patients with atherosclerosis

OBJECTIVE: This study was performed to investigate the endothelium-dependent relaxation and contractile responses to endothelin-1 in subcutaneous resistive arteries from Caribbean patients with advanced atherosclerotic femoro-crural arterial disease. DESIGN AND METHODS: Small subcutaneous arteries (inner diameter 200 um) from control subjects (n=8) and atherosclerotic patients (n=8) were dissected from fat biopsies obtained at routine vascular surgery and mounted in vitro on a wire-myograph measuring parietal tension under isometric conditions. RESULTS: Acetylcholine-induced relaxation (10-6 M) was significantly reduced in pre-contracted arteries from atherosclerotic patients (24 + or - 16 percent vs 17 percent in control, p<0.001). Smooth muscle relaxation to sodium nitroprusside was comparable in both groups. Contractions elicited by endothelin-1 (10-9 M) were significantly lower and almost suppressed in both the atherosclerotic group (1.2 + or - 0.8 Kpa) and in the hypertensive subgroup of control subjects (n=4, 1.2= 0r - 1.2 Kpa) comparatively to normotensive control subjects (12.3 + or - 6.9 Kpa, p<0.001). Contractile responses induced by endothelin-1 at higher concentrations (10-8 - 10-7 M), noradrenaline and hyperosmolar potassium were comparable in both groups. CONCLUSIONS: These data suggest a specific impairment of both endothelium-dependent relaxation and contractility in lower limb subcutaneous resistive arteries from Caribbean patients with atherosclerotic femoro-crural arterial disease. These changes in vessels which largely determine proximal vascular resistance may contribute to ischaemic complications in this vascular bed including skin ulcerations and gangrene.(Au)

Effects of ackee fruit extracts on bronchomotor tone in rats

The unripe ackee fruit, when eaten, is known to cause serious clinical manifestations, including vomiting, hypoglycaemia and acidosis. The effects, of various extracts from the arilli of the unripe fruit (including hypoglyin-A) on the lungs from rats were examined in an in vitro preparation. All the extracts were found to induce moderately severe broncho-constriction, indicating a possible contribution of these effects to the observed toxicity of ackee (AU)

In vitro human placental perfusion studies cholinergic activity in normal subjects and in toxaemia of pregnancy

The present study was designed to investigate acetylcholine (ACh) concentration in normal and toxaemic placentae. The perfusate from placental lobules was collected at different time intervals and analysed, by bioassay, for ACh. The results showed that ACh concentration was time-dependent, attaining its highest value by 90 minutes (74.465 ñ 0.76 10-9 g/ min/g), which was maintained for up to 180 minutes placentae. Similar observations were made in the toxaemic samples, but the values were significantly lower, when compared to the control group (44.36 ñ 1.54 10-9g/min/gt at 90 minutes). This study demonstrated active secretion of Ach by the placentae and the occurrence of low ACh concentration in toxeamia. It is postulated that low ACh could probably interfere with local transport mechanism and account for low birth weights in toxaemia.(AU)

Long-term effects of marihuana smoke on uterine contractility and tumour development in rats

The present investigation considered the role of acute and chronic marihuana smoking, as well as crude extracts of marihuana (ME), on uterine contractions and tumour development. The contractions and the electrical activity were recorded on isolated superfused rats' uteri. Enhanced spontaneous activity and contractile responses were observed following exposure to marihuana smoke. Atropine failed to block contractile responses with ME following chronic smoke exposure. It is suggested that ME contains both contractile and relaxing properties. Chronic exposure to marihuana smoke resulted in appearance of various tumours in 50 percent of experimental animals. This study suggested far-reaching consequences on reproductive activity following chronic use of marihuana (AU)

Contractile response of uterine smooth muscle to acetylcholine and marijuana extract

Marijuana extract (ME) is known to influence smooth muscle activity. This study was designed to investigate the effect of crude ME on rat uterine muscle and to explain the mechanism of action using antagonists such as atropine, ergometrine and propranolol. The contractions and the electrical activity were recorded on isolated superfused rat uteri. It is speculated that ME by its uterine stimulation action compromise uterine blood and may affect oxygen/nutrient transfer. The implication of this to the fetus is discussed. (AU)

Bronchomotor tone in protein-energy malnutrition

The study examined the reactivity of the tracheobronchial tree of rats maintained on low protein and tryptophan-deficient diets. It was found that: (1) Rats maintained on 5 percent protein or triptophan-deficient diets showed little or no weight gain. A 15 percent protein diet was adequate for normal growth of female rats, but not of male rats. (2) Airways of malnourished rats showed significant bronchoconstriction when treated to an acetylcholine (AcCH) concentration of 10 to the 11 power M. The treshold concentration of AcCh for normal rats was 10 to the -5 M. Airways of malnourished rats were also more sensitive to cold. (3) Rehabilitation of the malnourished rats attenuated the response to AcCh. Recovery, however, was not complete. (4) Prior application of phentolamine and atropine markedly reduced the sensitivity of the airways of malnourished rats to AcCh. The results seem to indicate that O-adrenoceptors and the vagus nerve may be involved in the observed increased reactivity of airways of malnourished rats.(AU)