ISSN:
1432-136X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary The effects of increased fluid volume in the closed vascular system on circulation were studied in the leech (Hirudo medicinalis) by intravascular pressure recordings and blood flow measurements. Significant increases in blood volume were achieved by crop loading with hyposmotic (72 mOsmol·kg−1 H2O) or hyperosmotic (300 mOsmol·kg−1 H2O) salt solutions or by infusion of isosmotic saline (200 mOsmol·kg−1) into the vascular system. During the high-pressure (HIP) phase, which maintains the rear-to-front circulation, systolic blood pressure in the heart was not affected. An increase in systolic pressure in the heart was observed during the low-pressure (LOP) phase, which supplies the segmental circulation. Heart rate was not changed by crop loading with hyposmotic saline or by vascular infusion. Heart rate decreased after crop loading with hyperosmotic saline. Blood flow rate in the dorsal vessel was increased by crop loading with hyposmotic saline, but not after crop loading with hyperosmotic saline. In all cases the diameter of the dorsal vessel was not affected. A possible mechanism controlling blood pressure and blood flow in the vascular system is discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00692563
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