The Impact of Biomedical Bleeding on Horseshoe Crab, Limulus polyphemus , Movement Patterns on Cape Cod, Massachusetts

The purpose of this study was to determine if bleeding, for biomedical purposes, influenced the behavior of horseshoe crabs, Limulus polyphemus . In the summer of 2001, ten bled and ten control (unbled) female horseshoe crabs were tracked for 26 days using acoustic telemetry in a small estuary on Cape Cod, Massachusetts. All but three crabs, two bled and one control, were located during the study period. No mortality was observed in the control group, while 20% mortality was observed within the bled group. There was no significant difference in the average rate of movement or in the spatial distribution within the estuary between the two groups. However, a difference was detected in the movement patterns. Horseshoe crabs from the bled group had a random direction of movement compared to the directional movement pattern of the control group, suggesting that the bled crabs experienced more disorientation.     

Effect of acute oral administration of captopril and MK-421 on vascular angiotensin converting enzyme activity in the spontaneously hypertensive rat

Vascular angiotensin converting enzyme (ACE) may be important as a potential site of action for the antihypertensive effect of ACE inhibitors. ACE activity, estimated by hydrolysis of [³H] HipGlyGly, was similar in the aorta, mesenteric and carotid arteries of SHR. ACE activity in veins was not as consistent and was significantly lower in the jugular veins and vena cava of SHR than in the arteries. Nevertheless, ACE activity in all the blood vessels examined, although less than lung ACE activity, was higher than ACE activity found in other tissues such as brain, heart and kidney. Equieffective antihypertensive doses of captopril (10 mg/kg p.o.) and MK-421 (1.0 mg/kg p.o.) dramatically inhibited ACE activity in all the arteries and veins examined. Maximal ACE inhibition occured within 15 minutes after the oral administration of captopril. In contrast, maximal ACE inhibition was slower in onset and of longer duration after MK-421 than after captopril for all the vessels. Thus, relatively high ACE activity can be measured in both arteries and veins from the spontaneously hypertensive rat (SHR) and ACE was dramatically inhibited after antihypertensive oral doses of captopril or MK-421. Furthermore, vascular ACE inhibition can be used to compare the onset and duration of activity of ACE inhibitors; MK-421 has a longer onset and duration in SHR than captopril based on inhibition of ACE in blood vessels.