Ultrastructural Alterations in Ischaemic Lesion of Small Intestinal Mucosa in Experimental Superior Mesenteric Artery Occlusion

Abstract

Aho, A. J., Arstila, A. U., Ahonen, J., Inberg, M. V. & Scheinin, T. M. 1973. Ultrastructural Alterations in Ischaemic Lesion of Small Intestinal Mucosa in Experimental Superior Mesenteric Artery Occlusion. Effect of Oxygen Breathing. Scand. J. Gastroent. 8, 439-447.

Ultrastructural changes in canine intestinal (small bowel) mucosal cells caused by superior mesenteric arterial occlusion (SMAO) were studied in sequential biopsies before and l5 minutes to 5 hours after the occlusion. The effects of room air and oxygen breathing during arterial occlusion were compared. During room air breathing, occasional changes in cellular ultrastructure were recorded only after 30 minutes of occlusion. Mitochondrial changes, clumping of nuclear chromatin, and dilatation of endoplasmic reticulum were among the first signs of damage. Later, breakage of microvilli and swelling of mitochondria were observed. The changes were not uniform but varied from cell to cell, with apparently normal cells being observed among damaged ones. After two hours, junctional complexes between many cells broadened, cells tended to detach from each other through cell membrane disruption, and changes in intracellular organelles progressed. Clearly lethal changes first became apparent in places after four hours of arterial occlusion. The morphological changes corresponded to the biochemical enzyme changes noted earlier by us, except for the early increase in LDH activity of the thoracic duct lymph. Ventilation with pure oxygen protected the intestinal mucosal cells during arterial occlusion, although dilatation of rough endoplasmic reticulum, as an isolated change, was observed fairly early.

Key-words::

• Oxygen therapy
• superior mesenteric arterial occlusion (SMAO)
• ultrastructure of ischaemic intestinal mucosal damage