Rp camp

Before drug infusion, mice were gently restrained, and dummy cannula were replaced with injection cannula that extended 1 mm from the tip of the guide cannula. For protein kinase A (PKA) inhibition during a stress-inducing session, saline or Rp-cAMP (Santa Cruz Biotechnology, TX, USA) was infused into the lateral ventricle or the BLA using a 10 μL Hamilton syringe under infusion pump control. For chemogenetic inhibition of OFC–BLA transmission, saline or clozapine n-oxide (CNO, Hello Bio, Bristol, UK) were infused into the BLA.

Single right ventricular myocytes were isolated from CTL and PAB rats. Rats were anesthetized with ketamine (0.1 mg/g) and xylazine (0.01 mg/g) until loss of toe pinch reflex, and hearts were excised and mounted on a Langendorff apparatus. Hearts were retrogradely perfused with nominally Ca²⁺‐free Tyrode's solution for 5 min followed by Minimal Essential Medium Eagle (MEM) solution containing 20 µM Ca²⁺ and 22.5 µg/ml Liberase Blendzyme TH (Roche Applied Science) for 25–45 min at 37°C. The right ventricular free wall was removed from the heart, minced, filtered and washed in MEM solution containing 50 µM Ca²⁺ and 10 mg/ml bovine serum albumin. Isolated cells were kept in MEM solution with 50 µM Ca²⁺ at room temperature (22–24°C) until indicator dye loading and subsequent experimentation. For some experiments, the cMLCK inhibitor ML‐7 (Tocris) or the PKA inhibitor Rp‐cAMPS (Santa Cruz) was used. Myocytes were treated for 5 min with 10 µM ML‐7 or 100 µM Rp‐cAMPS in normal Tyrode's solution before data acquisition.