Search PubMed⌕ Search

Biomedical subjects

S Nordgren

Publications and source records attributed to S Nordgren.

87 records · Page 5Linked to original sources
PubMed1983

The effects of 5-hydroxytryptamine on large intestinal motility and blood flow in the cat.

The effects of 5-HT on proximal colonic and rectal motility and total colonic blood flow were studied in anaesthetized cats and compared with those evoked by pelvic nerve stimulation. Vasodilator responses, consistently elicited by low doses (5-10 micrograms/min close i.a.) and intermediate doses (10-50 micrograms/min) of 5-HT were invariably abolished by hexamethonium indicating a nerve mediated response. Simultaneously to the vasodilator response both cholinergic and non-cholinergic hexamethonium sensitive non-adrenergic motility responses were evoked in the proximal colon. Furthermore non-cholinergic, non-adrenergic inhibitory neurons were excited. In the rectum excitation of such inhibitory neurons was the most consistent finding. The mechanisms behind the nerve mediated vascular and motility responses seem to differ as only the vascular effects were blocked by dihydroergotamine. The nerve mediated responses were in many respects similar to those evoked by pelvic nerve stimulation indicating that 5-HT exerts its effects on the same instrinsic neurons as the pelvic nerves. At intermediate and high doses (50-100 micrograms/min) the effects exerted on the instrinsic reflex arcs were modulated by direct effects on the smooth muscle.

Animals↗
PubMed1982

Pressure studies on the continent reservoir ileostomy.

The continent Koch ileostomy constitutes a major improvement in the quality of life for patients requiring an ileostomy. Complete continence is achieved in most patients, although the mechanisms underlying this control of fecal flow are poorly understood. Pressure studies on the pouch, the nipple valve and the outlet were preformed and results showed the presence of a high pressure zone in the nipple valve relative to the pouch. The high pressure zone maintained, even when the intra-abdominal pressure was raised or during contractions of the pouch, and most likely, contributes to continence. The pressure in the nipple valve and outlet was further intermittently increased by spontaneously occurring phasic and tonic contractions. Distention of the pouch with air caused a tonic contraction that was first recorded from the pouch and that traveled aborally along the intestinal layers of the intususcepted nipple valve and the outlet. By frequent emptying of the pouch, such contractions are avoided, and the risk of desusception of the nipple valve may be reduced.

Adolescent↗
PubMed1981

Studies on the atropine-resistant sacral parasympathetic vascular and motility responses in the cat colon.

1. Pelvic nerve stimulation in atropinized cats elicits a sustained contraction of the proximal colon and a relaxation of the rectum. Concomitantly there is an immediate but transient vasodilatation which is followed by recurrent increases and a slight post-stimulatory hyperaemia. Direct stimulation of the pelvic nerve produces secretion of colonic kallikrein and activation of the plasma kinin system. The present study examines whether Trasylol, which inhibits the kinin system, affects the atropine-resistant responses observed on pelvic nerve stimulation. 2. After I.V. or close I.A. administration of Trasylol, the initial vasodilatation on pelvic nerve stimulation was markedly reduced and in a few experiments completely blocked. The recurrent blood flow increases and the post-stimulatory hyperaemia observed on prolonged stimulation were completely abolished. In contrast the proximal colonic contraction and the rectal relaxation appeared unchanged after Trasylol. 3. The reactivity of the vascular bed after Trasylol injection was studied by recording the changes of vascular resistance following sympathetic vasoconstrictor fibre activation and infusion of bradykinin before and after Trasylol injection. The responses were quantitatively unchanged excluding an unspecific interference with nervous transmission or vascular smooth muscle reactivity. 4. The results show that the atropine-resistant vasodilatation in the cat colon as elicited by pelvic nerve stimulation is partly abolished by a kallikrein inhibitor. This observation lends further support to the hypothesis that kinins might be involved in this response. The motor response, however, appears not be dependent on such a mechanism.

Animals↗
PubMed1981

Vascular responses of small intestine and liver to regional infusion of vasopressin.

The vascular responses of the small intestine and liver to regional infusion of vasopressin were measured continuously and synchronously in anaesthetized cats. When infused into the superior mesenteric artery there was a marked initial blood flow reduction (peak response) followed by a sustained but moderately reduced flow (steady state). Corresponding to the peak response the portal pressure fell significantly. This reduction was only transient, however. Vasopressin infused into the hepatic artery caused if anything only a shortlasting decrease of hepatic flow. Concomitantly there was also a transient decrease of portal pressure. The findings indicate that continuous regional infusion of vasopressin causes a considerable reduction of intestinal blood flow without interfering with hepatic arterial circulation.

Animals↗
PubMed1980

Adjustments of hepatic and small intestine blood flow on selective vasoconstrictor fibre stimulation.

The mutual changes in hepatic and small intestinal blood flow on selective nervous stimulation of the periarterial vasoconstriction fibres, were studied in anaesthetized cats. Occlusion of the hepatic artery did not change portal blood flow, whereas occlusion of superior mesenteric blood flow caused a significant increase in hepatic arterial flow. Stimulation of the hepatic sympathetic nervous supply caused a phasic blood flow response with a marked transient peak flow reduction of hepatic arterial blood flow. The magnitude of the peak response varied with the frequency of the stimulation. Despite continuous stimulation the first phase went over into a second phase of less pronounced vasoconstriction. This "steady state" blood flow, was maintained at about 20% below the control level, irrespective of stimulation frequency. Corresponding in time with the peak vasoconstriction there was a transient increase of portal pressure. Sympathetic nerve stimulation increased portal pressure even on occlusion of the hepatic artery. Stimulation of the mesenteric sympathetic nerves evoked the characteristic transient peak vasoconstrictor response consisting of two phases, a brief intense peak resistance response followed by a second phase of less pronounced but generally well maintained constriction. Simultaneously a slight reduction of portal pressure and hepatic arterial vascular resistance was regularly seen. In contrast to the observations in the hepatic arterial circuit the magnitude of this "steady state" blood flow in the small intestine was dependent on the rate of the stimulation, however. On simultaneous stimulation of the hepatic and mesenteric sympathetic nerves the hemodynamic responses were largely the same as when these nerves were stimulated separately. The portal pressure affecting mean capillary pressure in the intestine differed, however. Small and variable pressure changes were followed by rapid return towards control and during steady state it did not differ from the prestimulatory level.

Adrenergic Fibers↗
PubMed1980

Evidence for a dual pelvic nerve influence on large bowel motility in the cat.

1. The effects of efferent electric pelvic nerve stimulation on colorectal motility and blood flow with emphasis on the motor responses in consecutive colonic and rectal segments were studied in anaesthetized cats. It was considered of particular interest to explore whether selective pharmacological blockade and graded nerve stimulations might reveal the presence of functionally differentiated efferent fibres controlling colonic motility.2. Pelvic nerve stimulation induced immediate and sustained colorectal contractions and a simultaneous increase of the over-all colonic blood flow. The excitatory responses declined immediately on cessation of a shortlasting stimulation (< 2 min); after a longlasting one, however, the rectal contraction was maintained for several min.3. The colonic contraction on pelvic nerve stimulation remained unchanged after atropine but was delayed in onset. Moreover, in the transverse and distal colon it was preceded by a relaxation which was most pronounced in the distal part. The vasodilator response was unchanged.4. After atropine the rectal segment showed a purely relaxatory response. Despite continuous pelvic nerve stimulation the relaxation vanished, however, and rectal volume returned to resting level with 3-5 min. On cessation of such a prolonged stimulation there was a marked rectal ;after-contraction'.5. The excitation thresholds for the efferent nerve fibres eliciting these different responses could not be separated. The motility and the vasodilator responses were not influenced by adrenergic or by serotoninergic blockade.6. The results indicate that direct preganglionic stimulation of the cat pelvic nerves activates intramural cholinergic excitatory neurones as well as non-cholinergic excitatory neurones and furthermore, non-adrenergic non-cholinergic inhibitory neurones, which together result in most complex colonic and rectal motor responses. From a functional point of view these centrally controlled responses may well be independently controlled by separate preganglionic neurones though they do not differ concerning excitation thresholds.7. The effects are consistent with a dual function of the distal colon and rectum. Such a dual parasympathetic influence on the large bowel simulates the vagal control of the stomach, where specific vagal relaxatory fibres convey a reflex widening of the corpus-fundus reservoir during food intake.

Animals↗
PubMed1979

Faecal excretion of intravenously injected 14C-cholic acid in patients with conventional ileostomy and in patients with continent ileostomy reservoir.

Bile salt absorption, as determined by the faecal excretion in i.v. injected 14C-cholic acid (FBS) was studied in 13 ileostomy patients before and after conversion to Kock's continent ileostomy reservoir. The result was compared with that obtained in 8 ileostomy patients in whom about 50 cm of the terminal ileum has also been removed. As compared with 16 healthy controls, FBS was moderately increased in the conventional ileostomy patients, but still within normal limits. After conversion to ileostomy reservoir all patients had pathological FBS, although less severe than in the ileostomy patients with ileal resection. Bacterial contamination probably contributes more than the structural mucosal changes to the bile malabsorption in the pouch, whereas reduced mucosal surface and short small-intestinal transit time are the main causes of malabsorption in ileostomy patients in whom an appreciable amount of the terminal ileum has been resected.

Adult↗
PubMed1978

Mobilization of colonic kallikrein following pelvic nerve stimulation in the atropinized cat.

1. Pelvic nerve stimulation (p.n.s.) in cats induces atropine-resistant colonic vasodilatation and colonic contraction. The effects of this on cat colon are mimicked by synthetic bradykinin infusions. The present study examines the effect of p.n.s. on the activation of kallikrein, the kinin-forming enzyme present in colonic tissue and its effects on the plasma kinin system in the atropinized cat.2. Mean level (+/- S.D.) of mucosal kallikrein was found to be about 37 times higher in unstimulated colonic mucosa (300 +/- 100 ng bradykinin equivalents min(-1)g(-1)) than in the underlying muscle (8.2 +/- 6.3 ng bradykinin equiv min(-1)g(-1)).3. After a p.n.s. of 5 min, mean kallikrein level in colonic muscle was 7.3 +/- 3.5 ng bradykinin equiv min(-1)g(-1), which was not significantly different from the control muscle kallikrein. However, there was an 86% fall in mucosal kallikrein to 41.3 +/- 34.7 ng bradykinin equiv min(-1)g(-1) after 5 min p.n.s., indicating a rapid activation and secretion of mucosal kallikrein.4. Secretion of mucosal kallikrein was paralleled by specific depletion of plasma kininogen, the precursor of active kinin in blood draining the colon. The mean plasma kininogen level fell to 79 and 68% of the prestimulated value (3.1 +/- 1.1 S.D. mug bradykinin equiv per ml. plasma) after 5 and 10 min p.n.s. respectively. Total plasma protein and haematocrit remained unaltered excluding non-specific changes due to protein extravasation or haemodilution and indicating utilization of the plasma kinin precursor.5. Following 2 hr p.n.s., raised levels of kallikrein were detected in both colonic muscle (28 +/- 2.0 bradykinin equiv min(-1)g(-1)) and mucosa 434 +/- 118 ng bradykinin equiv min(-1)g(-1)). Preliminary studies using a kallikrein inhibitor indicated that the increased kallikrein levels originated from plasma.6. Direct stimulation of the parasympathetic pelvic nerve in the atropinized cat thus produced activation of the plasma kinin system in the colon and formation of free kinins may be responsible for the mucosal vasodilatation and strong motor contraction which is not blocked by large doses of atropine. The observation that prolonged stimulation causes extravasation of plasma kallikrein, a potential inflammatory mediator, into the tissues may be of clinical significance.

Animals↗
PubMed1978

Sexual dysfunction following proctocolectomy.

122 patients, 66 men and 56 women, operated upon by proctocolectomy were interviewed by means of a detailed questionaire regarding any significant change in sexual function. In the majority of the patients (70% of the men and 87% of the women) the sexual relationships were considered to be unchanged or even enhanced. Impaired function was reported by 19 men (29%) and seven women (12%). Male sexual dysfunction consisted of impotence and abolition of ejaculation. True impotence occurred in five men, all above 40 years of age, corresponding to an incidence of 25%. Loss of ejaculation occurred even in young people (about 7%) but was more common in elderly patients (15%). Female dysfunction consisted of dyspareunia and/or inability to achieve orgasm. On the basis of the present results it appears unlikely that impotence is caused by the operative trauma per se. On the other hand loss of ejaculation is probably due to injury of the presacral nerves. Postoperative impotence might probably be improved by medical information and encouragement. Particular precautions during operation might reduce ejaculatory disorders. Careful handling and proper treatment of the perineal wound might prevent scarring and stricture of the posterior aspect of the vulva, a condition that appears to be a common cause of dyspareunia.

Adult↗
PubMed1978

Blood pressure changes in the marginal artery of the colon following occlusion of the inferior mesenteric artery.

The perfusion pressure in the marginal artery of the descending colon was measured continuously at laparotomy in eight patients and the effect of sudden occlusion of the inferior mesenteric artery recorded. Three patients with ulcerative colitis, all in their early 30s, and five elderly patients with colonic or rectal carcinoma were studied. In all patients occlusion caused an initial and marked pressure drop, which remained reduced at a critically low level in two of the elderly patients. Such a reduction in perfusion pressure is probably still insufficient to interfere with the nourishment of the terminal part of the colon provided that the systemic pressure is kept at a normal level. However, since in many patients there is a sharp drop in systemic blood pressure during the recovery phase after surgery, it appears likely that the perfusion pressure in the marginal artery may in those cases be insufficient to maintain an adequate blood flow to the colon despite the inherent tendency of "auto-regulation" in this vascular bed. The results of the present study indicate that, contrary to previous belief, ligation of the inferior mesenteric artery may increase the risk of ischaemia in the terminal part of the descending colon, leading to anastomotic dehiscence after anterior resection, or sloughing after a "pull-through" operation. This complication could probably be prevented by a more generous resection of the sigmoid and descending colon, thus reducing the length of the anastomosis formed by the arc of Riolan and by careful maintenance of an adequate blood pressure during the recovery phase.

Adult↗
PubMed1977

Vascular responses to mechanical stimulation of the mucosa of the cat colon.

Mechanical stimulation of the mucosa of the proximal colon evoked a hyperemia which also could be elicited when severing the autonomic fibres to the colon. Mechanical stimulation of the distal colon produced a hyperemia which, on the other hand, was abolished by cutting the pelvic nerves. Afferent pelvic nerve stimulation evoked a response similar to that seen when stimulating the distal colon. Adrenergic and cholinergic receptor blockers did not affect the studied colonic vasodilations. Dihydroergotamine, given in doses abolishing the vascular effects of i.a. injected 5-hydroxytrptamine, abolished the hyperemia to mechanical stimulation of the proximal colon but not that of the pelvic stimulation. It is concluded that a local nervous vasodilator reflex exists in the proximal colon similar to that earlier demonstrated in the small bowel (Biber et al. 1971) and that the reflex vasodilatation evoked by mechanical stimulation in the distal colon is mediated via the pelvic nerves. Hence, the vascular control differs in the proximal and in the distal parts of the colon.

Animals↗