Perfused rat hindlegs. A model to study plasminogen activator release

Area of Science:

• Biochemistry
• Physiology
• Pharmacology

Background:

• Tissue-type plasminogen activator (t-PA) is crucial for fibrinolysis.
• Understanding t-PA release mechanisms is vital for therapeutic applications.
• Isolated perfused organ models offer controlled environments to study physiological responses.

Purpose of the Study:

• To investigate the release of tissue-type plasminogen activator (t-PA) activity from isolated rat hindlegs.
• To identify potent compounds that induce t-PA release.
• To examine the effects of repeated and varied compound stimulation on t-PA release.

Main Methods:

• Utilized an isolated perfused rat hindleg model.
• Administered various compounds to induce activator release.
• Measured t-PA activity in perfusates using a standardized assay (Ploug Units/minute).
• Assessed responses to single, repeated, and sequential different compound stimulations.

Main Results:

• Thrombin, bradykinin, and eldooisin were identified as potent inducers of t-PA release.
• Maximum release reached approximately 6 Ploug Units/minute.
• Repeated stimulation with the same compound led to diminished release.
• Subsequent stimulation with unrelated compounds did not reduce, and occasionally enhanced, t-PA release.
• A good correlation was observed between in vitro and in vivo compound-induced t-PA release.

Conclusions:

• Specific compounds effectively stimulate t-PA release in a perfused vascular bed.
• The hindleg vasculature exhibits desensitization to repeated stimulation by the same agent.
• Cross-reactivity or synergistic effects may occur with unrelated t-PA releasing agents.
• Findings in the perfused hindleg model correlate well with in vivo observations, suggesting its validity for studying t-PA release.