PTH-receptors regulate norepinephrine release in human heart and kidney

Area of Science:

• Endocrinology
• Cardiovascular Physiology
• Nephrology

Background:

• Chronic renal failure and hyperparathyroidism are linked to increased sympathetic nervous system activity.
• Peptide hormones, including parathyroid hormone (PTH), can modulate neurotransmitter release through prejunctional receptors.

Purpose of the Study:

• To investigate if parathyroid hormone fragment (1-34) (hPTH(1-34)) enhances neuronal norepinephrine (NE) release in human heart and kidney.
• To explore functional differences between PTH1 and PTH2 receptors using specific agonists and antagonists.

Main Methods:

• Human atrial and renal tissues were incubated with radiolabeled NE and superfused.
• Electrical stimulation was used to measure NE release, assessed by tritium outflow.
• Real-time PCR (RT-PCR) was employed to detect PTH receptor expression in cardiac and renal tissues.

Main Results:

• hPTH(1-34) and 8-bromo-cAMP significantly increased NE release in human atria and renal cortex.
• The PTH1 receptor antagonist blocked the facilitatory effect of hPTH(1-34), confirming receptor specificity.
• Tuberoinfundibular peptide of 39 residues (TIP-39) demonstrated a different effect, decreasing NE release in atria, suggesting distinct receptor actions.

Conclusions:

• Parathyroid hormone facilitates norepinephrine release in the human atria and renal cortex through PTH1 receptor activation.
• Elevated PTH levels in chronic renal failure may contribute to sympathetic overactivity and cardiovascular mortality in end-stage renal disease patients.