Alpha-lactorphin and beta-lactorphin improve arterial function in spontaneously hypertensive rats

Area of Science:

• Cardiovascular Physiology
• Pharmacology
• Biochemistry

Background:

• Spontaneously hypertensive rats (SHR) exhibit impaired vascular relaxation.
• Milk-derived peptides are being investigated for potential health benefits, including blood pressure regulation.

Purpose of the Study:

• To investigate the antihypertensive mechanisms of alpha-lactorphin and beta-lactorphin on vascular function in vitro.
• To compare the effects of these tetrapeptides on endothelial-dependent and independent relaxation in hypertensive rats.

Main Methods:

• In vitro study using mesenteric arterial preparations from spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats.
• Assessment of vascular relaxation responses to acetylcholine (ACh) and sodium nitroprusside (SNP).
• Involvement of nitric oxide (NO) and other pathways was examined using specific inhibitors (L-NAME, TEA, diclofenac).

Main Results:

• Endothelium-dependent relaxation to ACh was reduced in SHR compared to WKY rats.
• Both alpha-lactorphin and beta-lactorphin augmented ACh-induced relaxation in SHR, an effect abolished by L-NAME, indicating NO involvement.
• Beta-lactorphin also augmented endothelium-independent relaxation to SNP in SHR.
• Neither tetrapeptide affected vascular responses in normotensive WKY rats.

Conclusions:

• Alpha-lactorphin and beta-lactorphin improve vascular relaxation in adult SHR in vitro.
• Alpha-lactorphin's beneficial effect is primarily on endothelial function via nitric oxide.
• Beta-lactorphin enhances both endothelial-dependent and independent relaxation pathways.