I have an increase in arterial resistance coincides with a decreased heart rate, what can be the cause of this 'in vivo'?

Cushing's Reflex. There is a clinical entity called cushing's reflex where this physiology comes into play. This happens when there is a bleed in the brain. This leads to increased arterial resistance in the brain, and through a series of complex feedback loops in the adrenergic system, leads to reflexive bradycardia.